gecko-dev/docshell/base/nsDocShell.h

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=4 sw=4 et tw=80:
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef nsDocShell_h__
#define nsDocShell_h__

#include "nsITimer.h"
#include "nsContentPolicyUtils.h"
#include "nsIDocShell.h"
#include "nsIDocShellTreeItem.h"
#include "nsIBaseWindow.h"
#include "nsIScrollable.h"
#include "nsITextScroll.h"
#include "nsIContentViewerContainer.h"
#include "nsIDOMStorageManager.h"
#include "nsDocLoader.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/WeakPtr.h"
#include "mozilla/TimeStamp.h"
#include "GeckoProfiler.h"
#include "mozilla/dom/ProfileTimelineMarkerBinding.h"
#include "jsapi.h"

// Helper Classes
#include "nsCOMPtr.h"
#include "nsPoint.h" // mCurrent/mDefaultScrollbarPreferences
#include "nsString.h"
#include "nsAutoPtr.h"
#include "nsThreadUtils.h"
#include "nsContentUtils.h"
#include "TimelineMarker.h"

// Threshold value in ms for META refresh based redirects
#define REFRESH_REDIRECT_TIMER 15000

// Interfaces Needed
#include "nsIDocCharset.h"
#include "nsIInterfaceRequestor.h"
#include "nsIRefreshURI.h"
#include "nsIWebNavigation.h"
#include "nsIWebPageDescriptor.h"
#include "nsIWebProgressListener.h"
#include "nsIDocShellLoadInfo.h"
#include "nsIAuthPromptProvider.h"
#include "nsILoadContext.h"
#include "nsIWebShellServices.h"
#include "nsILinkHandler.h"
#include "nsIClipboardCommands.h"
#include "nsITabParent.h"
#include "nsCRT.h"
#include "prtime.h"
#include "nsRect.h"
#include "Units.h"

namespace mozilla {
namespace dom {
class EventTarget;
class URLSearchParams;
}
}

class nsDocShell;
class nsDOMNavigationTiming;
class nsGlobalWindow;
class nsIController;
class nsIScrollableFrame;
class OnLinkClickEvent;
class nsDSURIContentListener;
class nsDocShellEditorData;
class nsIClipboardDragDropHookList;
class nsICommandManager;
class nsIContentViewer;
class nsIDocument;
class nsIDOMNode;
class nsIDocShellTreeOwner;
class nsIGlobalHistory2;
class nsIHttpChannel;
class nsIPrompt;
class nsISHistory;
class nsISecureBrowserUI;
class nsIStringBundle;
class nsISupportsArray;
class nsIURIFixup;
class nsIURILoader;
class nsIWebBrowserFind;
class nsIWidget;
class ProfilerMarkerTracing;

/* load commands were moved to nsIDocShell.h */
/* load types were moved to nsDocShellLoadTypes.h */

/* internally used ViewMode types */
enum ViewMode {
    viewNormal = 0x0,
    viewSource = 0x1
};

//*****************************************************************************
//***    nsRefreshTimer
//*****************************************************************************

class nsRefreshTimer : public nsITimerCallback
{
public:
    nsRefreshTimer();

    NS_DECL_THREADSAFE_ISUPPORTS
    NS_DECL_NSITIMERCALLBACK

    int32_t GetDelay() { return mDelay ;}

    nsRefPtr<nsDocShell>  mDocShell;
    nsCOMPtr<nsIURI>      mURI;
    int32_t               mDelay;
    bool                  mRepeat;
    bool                  mMetaRefresh;
    
protected:
    virtual ~nsRefreshTimer();
};

typedef enum {
    eCharsetReloadInit,
    eCharsetReloadRequested,
    eCharsetReloadStopOrigional
} eCharsetReloadState;

//*****************************************************************************
//***    nsDocShell
//*****************************************************************************

class nsDocShell MOZ_FINAL : public nsDocLoader,
                             public nsIDocShell,
                             public nsIWebNavigation,
                             public nsIBaseWindow,
                             public nsIScrollable,
                             public nsITextScroll,
                             public nsIDocCharset,
                             public nsIContentViewerContainer,
                             public nsIRefreshURI,
                             public nsIWebProgressListener,
                             public nsIWebPageDescriptor,
                             public nsIAuthPromptProvider,
                             public nsILoadContext,
                             public nsIWebShellServices,
                             public nsILinkHandler,
                             public nsIClipboardCommands,
                             public nsIDOMStorageManager,
                             public mozilla::SupportsWeakPtr<nsDocShell>
{
    friend class nsDSURIContentListener;

public:
    MOZ_DECLARE_REFCOUNTED_TYPENAME(nsDocShell)
    // Object Management
    nsDocShell();

    NS_DECL_AND_IMPL_ZEROING_OPERATOR_NEW

    virtual nsresult Init() MOZ_OVERRIDE;

    NS_DECL_ISUPPORTS_INHERITED

    NS_DECL_NSIDOCSHELL
    NS_DECL_NSIDOCSHELLTREEITEM
    NS_DECL_NSIWEBNAVIGATION
    NS_DECL_NSIBASEWINDOW
    NS_DECL_NSISCROLLABLE
    NS_DECL_NSITEXTSCROLL
    NS_DECL_NSIDOCCHARSET
    NS_DECL_NSIINTERFACEREQUESTOR
    NS_DECL_NSIWEBPROGRESSLISTENER
    NS_DECL_NSIREFRESHURI
    NS_DECL_NSICONTENTVIEWERCONTAINER
    NS_DECL_NSIWEBPAGEDESCRIPTOR
    NS_DECL_NSIAUTHPROMPTPROVIDER
    NS_DECL_NSICLIPBOARDCOMMANDS
    NS_DECL_NSIWEBSHELLSERVICES
    NS_FORWARD_SAFE_NSIDOMSTORAGEMANAGER(TopSessionStorageManager())

    NS_IMETHOD Stop() MOZ_OVERRIDE {
        // Need this here because otherwise nsIWebNavigation::Stop
        // overrides the docloader's Stop()
        return nsDocLoader::Stop();
    }

    // Need to implement (and forward) nsISecurityEventSink, because
    // nsIWebProgressListener has methods with identical names...
    NS_FORWARD_NSISECURITYEVENTSINK(nsDocLoader::)

    // nsILinkHandler
    NS_IMETHOD OnLinkClick(nsIContent* aContent,
        nsIURI* aURI,
        const char16_t* aTargetSpec,
        const nsAString& aFileName,
        nsIInputStream* aPostDataStream,
        nsIInputStream* aHeadersDataStream,
        bool aIsTrusted) MOZ_OVERRIDE;
    NS_IMETHOD OnLinkClickSync(nsIContent* aContent,
        nsIURI* aURI,
        const char16_t* aTargetSpec,
        const nsAString& aFileName,
        nsIInputStream* aPostDataStream = 0,
        nsIInputStream* aHeadersDataStream = 0,
        nsIDocShell** aDocShell = 0,
        nsIRequest** aRequest = 0) MOZ_OVERRIDE;
    NS_IMETHOD OnOverLink(nsIContent* aContent,
        nsIURI* aURI,
        const char16_t* aTargetSpec) MOZ_OVERRIDE;
    NS_IMETHOD OnLeaveLink() MOZ_OVERRIDE;

    nsDocShellInfoLoadType ConvertLoadTypeToDocShellLoadInfo(uint32_t aLoadType);
    uint32_t ConvertDocShellLoadInfoToLoadType(nsDocShellInfoLoadType aDocShellLoadType);

    // Don't use NS_DECL_NSILOADCONTEXT because some of nsILoadContext's methods
    // are shared with nsIDocShell (appID, etc.) and can't be declared twice.
    NS_IMETHOD GetAssociatedWindow(nsIDOMWindow**) MOZ_OVERRIDE;
    NS_IMETHOD GetTopWindow(nsIDOMWindow**) MOZ_OVERRIDE;
    NS_IMETHOD GetTopFrameElement(nsIDOMElement**) MOZ_OVERRIDE;
    NS_IMETHOD GetNestedFrameId(uint64_t*) MOZ_OVERRIDE;
    NS_IMETHOD IsAppOfType(uint32_t, bool*) MOZ_OVERRIDE;
    NS_IMETHOD GetIsContent(bool*) MOZ_OVERRIDE;
    NS_IMETHOD GetUsePrivateBrowsing(bool*) MOZ_OVERRIDE;
    NS_IMETHOD SetUsePrivateBrowsing(bool) MOZ_OVERRIDE;
    NS_IMETHOD SetPrivateBrowsing(bool) MOZ_OVERRIDE;
    NS_IMETHOD GetUseRemoteTabs(bool*) MOZ_OVERRIDE;
    NS_IMETHOD SetRemoteTabs(bool) MOZ_OVERRIDE;

    // Restores a cached presentation from history (mLSHE).
    // This method swaps out the content viewer and simulates loads for
    // subframes.  It then simulates the completion of the toplevel load.
    nsresult RestoreFromHistory();

    // Perform a URI load from a refresh timer.  This is just like the
    // ForceRefreshURI method on nsIRefreshURI, but makes sure to take
    // the timer involved out of mRefreshURIList if it's there.
    // aTimer must not be null.
    nsresult ForceRefreshURIFromTimer(nsIURI * aURI, int32_t aDelay,
                                      bool aMetaRefresh, nsITimer* aTimer);

    friend class OnLinkClickEvent;

    // We need dummy OnLocationChange in some cases to update the UI without
    // updating security info.
    void FireDummyOnLocationChange()
    {
        FireOnLocationChange(this, nullptr, mCurrentURI,
                             LOCATION_CHANGE_SAME_DOCUMENT);
    }

    nsresult HistoryTransactionRemoved(int32_t aIndex);

    // Notify Scroll observers when an async panning/zooming transform
    // has started being applied
    void NotifyAsyncPanZoomStarted(const mozilla::CSSIntPoint aScrollPos);
    // Notify Scroll observers when an async panning/zooming transform
    // is no longer applied
    void NotifyAsyncPanZoomStopped(const mozilla::CSSIntPoint aScrollPos);

    // Add new profile timeline markers to this docShell. This will only add
    // markers if the docShell is currently recording profile timeline markers.
    // See nsIDocShell::recordProfileTimelineMarkers
    void AddProfileTimelineMarker(const char* aName,
                                  TracingMetadata aMetaData);
    void AddProfileTimelineMarker(mozilla::UniquePtr<TimelineMarker> &aMarker);

    // Global counter for how many docShells are currently recording profile
    // timeline markers
    static unsigned long gProfileTimelineRecordingsCount;
protected:
    // Object Management
    virtual ~nsDocShell();
    virtual void DestroyChildren() MOZ_OVERRIDE;

    // Content Viewer Management
    nsresult EnsureContentViewer();
    // aPrincipal can be passed in if the caller wants.  If null is
    // passed in, the about:blank principal will end up being used.
    nsresult CreateAboutBlankContentViewer(nsIPrincipal* aPrincipal,
                                           nsIURI* aBaseURI,
                                           bool aTryToSaveOldPresentation = true);
    nsresult CreateContentViewer(const char * aContentType, 
        nsIRequest * request, nsIStreamListener ** aContentHandler);
    nsresult NewContentViewerObj(const char * aContentType, 
        nsIRequest * request, nsILoadGroup * aLoadGroup, 
        nsIStreamListener ** aContentHandler, nsIContentViewer ** aViewer);
    nsresult SetupNewViewer(nsIContentViewer * aNewViewer);

    void SetupReferrerFromChannel(nsIChannel * aChannel);
    
    nsresult GetEldestPresContext(nsPresContext** aPresContext);

    // Get the principal that we'll set on the channel if we're inheriting.  If
    // aConsiderCurrentDocument is true, we try to use the current document if
    // at all possible.  If that fails, we fall back on the parent document.
    // If that fails too, we force creation of a content viewer and use the
    // resulting principal.  If aConsiderCurrentDocument is false, we just look
    // at the parent.
    nsIPrincipal* GetInheritedPrincipal(bool aConsiderCurrentDocument);

    // Actually open a channel and perform a URI load.  Note: whatever owner is
    // passed to this function will be set on the channel.  Callers who wish to
    // not have an owner on the channel should just pass null.
    // If aSrcdoc is not void, the load will be considered as a srcdoc load,
    // and the contents of aSrcdoc will be loaded instead of aURI.
    nsresult DoURILoad(nsIURI * aURI,
                       nsIURI * aReferrer,
                       bool aSendReferrer,
                       uint32_t aReferrerPolicy,
                       nsISupports * aOwner,
                       const char * aTypeHint,
                       const nsAString & aFileName,
                       nsIInputStream * aPostData,
                       nsIInputStream * aHeadersData,
                       bool firstParty,
                       nsIDocShell ** aDocShell,
                       nsIRequest ** aRequest,
                       bool aIsNewWindowTarget,
                       bool aBypassClassifier,
                       bool aForceAllowCookies,
                       const nsAString &aSrcdoc,
                       nsIURI * baseURI,
                       nsContentPolicyType aContentPolicyType);
    nsresult AddHeadersToChannel(nsIInputStream * aHeadersData, 
                                 nsIChannel * aChannel);
    nsresult DoChannelLoad(nsIChannel * aChannel,
                           nsIURILoader * aURILoader,
                           bool aBypassClassifier);

    nsresult ScrollToAnchor(nsACString & curHash, nsACString & newHash,
                            uint32_t aLoadType);

    // Returns true if would have called FireOnLocationChange,
    // but did not because aFireOnLocationChange was false on entry.
    // In this case it is the caller's responsibility to ensure
    // FireOnLocationChange is called.
    // In all other cases false is returned.
    bool OnLoadingSite(nsIChannel * aChannel,
                         bool aFireOnLocationChange,
                         bool aAddToGlobalHistory = true);

    // Returns true if would have called FireOnLocationChange,
    // but did not because aFireOnLocationChange was false on entry.
    // In this case it is the caller's responsibility to ensure
    // FireOnLocationChange is called.
    // In all other cases false is returned.
    // Either aChannel or aOwner must be null.  If aChannel is
    // present, the owner should be gotten from it.
    // If OnNewURI calls AddToSessionHistory, it will pass its
    // aCloneSHChildren argument as aCloneChildren.
    bool OnNewURI(nsIURI * aURI, nsIChannel * aChannel, nsISupports* aOwner,
                    uint32_t aLoadType,
                    bool aFireOnLocationChange,
                    bool aAddToGlobalHistory,
                    bool aCloneSHChildren);

    void SetReferrerURI(nsIURI * aURI);
    void SetReferrerPolicy(uint32_t referrerPolicy);

    // Session History
    bool ShouldAddToSessionHistory(nsIURI * aURI);
    // Either aChannel or aOwner must be null.  If aChannel is
    // present, the owner should be gotten from it.
    // If aCloneChildren is true, then our current session history's
    // children will be cloned onto the new entry.  This should be
    // used when we aren't actually changing the document while adding
    // the new session history entry.
    nsresult AddToSessionHistory(nsIURI * aURI, nsIChannel * aChannel,
                                 nsISupports* aOwner,
                                 bool aCloneChildren,
                                 nsISHEntry ** aNewEntry);
    nsresult AddChildSHEntryToParent(nsISHEntry* aNewEntry, int32_t aChildOffset,
                                     bool aCloneChildren);

    nsresult AddChildSHEntryInternal(nsISHEntry* aCloneRef, nsISHEntry* aNewEntry,
                                     int32_t aChildOffset, uint32_t loadType,
                                     bool aCloneChildren);

    nsresult LoadHistoryEntry(nsISHEntry * aEntry, uint32_t aLoadType);
    nsresult PersistLayoutHistoryState();

    // Clone a session history tree for subframe navigation.
    // The tree rooted at |aSrcEntry| will be cloned into |aDestEntry|, except
    // for the entry with id |aCloneID|, which will be replaced with
    // |aReplaceEntry|.  |aSrcShell| is a (possibly null) docshell which
    // corresponds to |aSrcEntry| via its mLSHE or mOHE pointers, and will
    // have that pointer updated to point to the cloned history entry.
    // If aCloneChildren is true then the children of the entry with id
    // |aCloneID| will be cloned into |aReplaceEntry|.
    static nsresult CloneAndReplace(nsISHEntry *aSrcEntry,
                                    nsDocShell *aSrcShell,
                                    uint32_t aCloneID,
                                    nsISHEntry *aReplaceEntry,
                                    bool aCloneChildren,
                                    nsISHEntry **aDestEntry);

    // Child-walking callback for CloneAndReplace
    static nsresult CloneAndReplaceChild(nsISHEntry *aEntry,
                                         nsDocShell *aShell,
                                         int32_t aChildIndex, void *aData);

    nsresult GetRootSessionHistory(nsISHistory ** aReturn);
    nsresult GetHttpChannel(nsIChannel * aChannel, nsIHttpChannel ** aReturn);
    bool ShouldDiscardLayoutState(nsIHttpChannel * aChannel);

    // Determine whether this docshell corresponds to the given history entry,
    // via having a pointer to it in mOSHE or mLSHE.
    bool HasHistoryEntry(nsISHEntry *aEntry) const
    {
        return aEntry && (aEntry == mOSHE || aEntry == mLSHE);
    }

    // Update any pointers (mOSHE or mLSHE) to aOldEntry to point to aNewEntry
    void SwapHistoryEntries(nsISHEntry *aOldEntry, nsISHEntry *aNewEntry);

    // Call this method to swap in a new history entry to m[OL]SHE, rather than
    // setting it directly.  This completes the navigation in all docshells
    // in the case of a subframe navigation.
    void SetHistoryEntry(nsCOMPtr<nsISHEntry> *aPtr, nsISHEntry *aEntry);

    // Child-walking callback for SetHistoryEntry
    static nsresult SetChildHistoryEntry(nsISHEntry *aEntry,
                                         nsDocShell *aShell,
                                         int32_t aEntryIndex, void *aData);

    // Callback prototype for WalkHistoryEntries.
    // aEntry is the child history entry, aShell is its corresponding docshell,
    // aChildIndex is the child's index in its parent entry, and aData is
    // the opaque pointer passed to WalkHistoryEntries.
    typedef nsresult (*WalkHistoryEntriesFunc)(nsISHEntry *aEntry,
                                               nsDocShell *aShell,
                                               int32_t aChildIndex,
                                               void *aData);

    // For each child of aRootEntry, find the corresponding docshell which is
    // a child of aRootShell, and call aCallback.  The opaque pointer aData
    // is passed to the callback.
    static nsresult WalkHistoryEntries(nsISHEntry *aRootEntry,
                                       nsDocShell *aRootShell,
                                       WalkHistoryEntriesFunc aCallback,
                                       void *aData);

    // overridden from nsDocLoader, this provides more information than the
    // normal OnStateChange with flags STATE_REDIRECTING
    virtual void OnRedirectStateChange(nsIChannel* aOldChannel,
                                       nsIChannel* aNewChannel,
                                       uint32_t aRedirectFlags,
                                       uint32_t aStateFlags) MOZ_OVERRIDE;

    /**
     * Helper function that determines if channel is an HTTP POST.
     *
     * @param aChannel
     *        The channel to test
     *
     * @return True iff channel is an HTTP post.
     */
    bool ChannelIsPost(nsIChannel* aChannel);

    /**
     * Helper function that finds the last URI and its transition flags for a
     * channel.
     *
     * This method first checks the channel's property bag to see if previous
     * info has been saved.  If not, it gives back the referrer of the channel.
     *
     * @param aChannel
     *        The channel we are transitioning to
     * @param aURI
     *        Output parameter with the previous URI, not addref'd
     * @param aChannelRedirectFlags
     *        If a redirect, output parameter with the previous redirect flags
     *        from nsIChannelEventSink
     */
    void ExtractLastVisit(nsIChannel* aChannel,
                          nsIURI** aURI,
                          uint32_t* aChannelRedirectFlags);

    /**
     * Helper function that caches a URI and a transition for saving later.
     *
     * @param aChannel
     *        Channel that will have these properties saved
     * @param aURI
     *        The URI to save for later
     * @param aChannelRedirectFlags
     *        The nsIChannelEventSink redirect flags to save for later
     */
    void SaveLastVisit(nsIChannel* aChannel,
                       nsIURI* aURI,
                       uint32_t aChannelRedirectFlags);

    /**
     * Helper function for adding a URI visit using IHistory.  If IHistory is
     * not available, the method tries nsIGlobalHistory2.
     *
     * The IHistory API maintains chains of visits, tracking both HTTP referrers
     * and redirects for a user session. VisitURI requires the current URI and
     * the previous URI in the chain.
     *
     * Visits can be saved either during a redirect or when the request has
     * reached its final destination.  The previous URI in the visit may be
     * from another redirect or it may be the referrer.
     *
     * @pre aURI is not null.
     *
     * @param aURI
     *        The URI that was just visited
     * @param aReferrerURI
     *        The referrer URI of this request
     * @param aPreviousURI
     *        The previous URI of this visit (may be the same as aReferrerURI)
     * @param aChannelRedirectFlags
     *        For redirects, the redirect flags from nsIChannelEventSink
     *        (0 otherwise)
     * @param aResponseStatus
     *        For HTTP channels, the response code (0 otherwise).
     */
    void AddURIVisit(nsIURI* aURI,
                     nsIURI* aReferrerURI,
                     nsIURI* aPreviousURI,
                     uint32_t aChannelRedirectFlags,
                     uint32_t aResponseStatus=0);

    // Helper Routines
    nsresult   ConfirmRepost(bool * aRepost);
    NS_IMETHOD GetPromptAndStringBundle(nsIPrompt ** aPrompt,
        nsIStringBundle ** aStringBundle);
    NS_IMETHOD GetChildOffset(nsIDOMNode * aChild, nsIDOMNode * aParent,
        int32_t * aOffset);
    nsIScrollableFrame* GetRootScrollFrame();
    NS_IMETHOD EnsureScriptEnvironment();
    NS_IMETHOD EnsureEditorData();
    nsresult   EnsureTransferableHookData();
    NS_IMETHOD EnsureFind();
    nsresult   RefreshURIFromQueue();
    NS_IMETHOD LoadErrorPage(nsIURI *aURI, const char16_t *aURL,
                             const char *aErrorPage,
                             const char16_t *aErrorType,
                             const char16_t *aDescription,
                             const char *aCSSClass,
                             nsIChannel* aFailedChannel);
    bool IsPrintingOrPP(bool aDisplayErrorDialog = true);
    bool IsNavigationAllowed(bool aDisplayPrintErrorDialog = true,
                             bool aCheckIfUnloadFired = true);

    nsresult SetBaseUrlForWyciwyg(nsIContentViewer * aContentViewer);

    static  inline  uint32_t
    PRTimeToSeconds(PRTime t_usec)
    {
      PRTime usec_per_sec = PR_USEC_PER_SEC;
      return  uint32_t(t_usec /= usec_per_sec);
    }

    inline bool UseErrorPages()
    {
      return (mObserveErrorPages ? sUseErrorPages : mUseErrorPages);
    }

    bool IsFrame();

    //
    // Helper method that is called when a new document (including any
    // sub-documents - ie. frames) has been completely loaded.
    //
    virtual nsresult EndPageLoad(nsIWebProgress * aProgress,
                                 nsIChannel * aChannel,
                                 nsresult aResult);

    // Sets the current document's current state object to the given SHEntry's
    // state object.  The current state object is eventually given to the page
    // in the PopState event.
    nsresult SetDocCurrentStateObj(nsISHEntry *shEntry);

    nsresult CheckLoadingPermissions();

    // Security checks to prevent frameset spoofing.  See comments at
    // implementation sites.
    static bool CanAccessItem(nsIDocShellTreeItem* aTargetItem,
                                nsIDocShellTreeItem* aAccessingItem,
                                bool aConsiderOpener = true);
    static bool ValidateOrigin(nsIDocShellTreeItem* aOriginTreeItem,
                                 nsIDocShellTreeItem* aTargetTreeItem);

    // Returns true if would have called FireOnLocationChange,
    // but did not because aFireOnLocationChange was false on entry.
    // In this case it is the caller's responsibility to ensure
    // FireOnLocationChange is called.
    // In all other cases false is returned.
    bool SetCurrentURI(nsIURI *aURI, nsIRequest *aRequest,
                       bool aFireOnLocationChange,
                       uint32_t aLocationFlags);

    // The following methods deal with saving and restoring content viewers
    // in session history.

    // mContentViewer points to the current content viewer associated with
    // this docshell.  When loading a new document, the content viewer is
    // either destroyed or stored into a session history entry.  To make sure
    // that destruction happens in a controlled fashion, a given content viewer
    // is always owned in exactly one of these ways:
    //   1) The content viewer is active and owned by a docshell's
    //      mContentViewer.
    //   2) The content viewer is still being displayed while we begin loading
    //      a new document.  The content viewer is owned by the _new_
    //      content viewer's mPreviousViewer, and has a pointer to the
    //      nsISHEntry where it will eventually be stored.  The content viewer
    //      has been close()d by the docshell, which detaches the document from
    //      the window object.
    //   3) The content viewer is cached in session history.  The nsISHEntry
    //      has the only owning reference to the content viewer.  The viewer
    //      has released its nsISHEntry pointer to prevent circular ownership.
    //
    // When restoring a content viewer from session history, open() is called
    // to reattach the document to the window object.  The content viewer is
    // then placed into mContentViewer and removed from the history entry.
    // (mContentViewer is put into session history as described above, if
    // applicable).

    // Determines whether we can safely cache the current mContentViewer in
    // session history.  This checks a number of factors such as cache policy,
    // pending requests, and unload handlers.
    // |aLoadType| should be the load type that will replace the current
    // presentation.  |aNewRequest| should be the request for the document to
    // be loaded in place of the current document, or null if such a request
    // has not been created yet. |aNewDocument| should be the document that will
    // replace the current document.
    bool CanSavePresentation(uint32_t aLoadType,
                               nsIRequest *aNewRequest,
                               nsIDocument *aNewDocument);

    // Captures the state of the supporting elements of the presentation
    // (the "window" object, docshell tree, meta-refresh loads, and security
    // state) and stores them on |mOSHE|.
    nsresult CaptureState();

    // Begin the toplevel restore process for |aSHEntry|.
    // This simulates a channel open, and defers the real work until
    // RestoreFromHistory is called from a PLEvent.
    nsresult RestorePresentation(nsISHEntry *aSHEntry, bool *aRestoring);

    // Call BeginRestore(nullptr, false) for each child of this shell.
    nsresult BeginRestoreChildren();

    // Method to get our current position and size without flushing
    void DoGetPositionAndSize(int32_t * x, int32_t * y, int32_t * cx,
                              int32_t * cy);
    
    // Call this when a URI load is handed to us (via OnLinkClick or
    // InternalLoad).  This makes sure that we're not inside unload, or that if
    // we are it's still OK to load this URI.
    bool IsOKToLoadURI(nsIURI* aURI);
    
    void ReattachEditorToWindow(nsISHEntry *aSHEntry);

    nsCOMPtr<nsIDOMStorageManager> mSessionStorageManager;
    nsIDOMStorageManager* TopSessionStorageManager();

    // helpers for executing commands
    nsresult GetControllerForCommand(const char *inCommand,
                                     nsIController** outController);
    nsresult EnsureCommandHandler();

    nsIChannel* GetCurrentDocChannel();

    bool ShouldBlockLoadingForBackButton();

    // Convenience method for getting our parent docshell.  Can return null
    already_AddRefed<nsDocShell> GetParentDocshell();

    // Check if we have an app redirect registered for the URI and redirect if
    // needed. Returns true if a redirect happened, false otherwise.
    bool DoAppRedirectIfNeeded(nsIURI * aURI,
                               nsIDocShellLoadInfo * aLoadInfo,
                               bool aFirstParty);
protected:
    nsresult GetCurScrollPos(int32_t scrollOrientation, int32_t * curPos);
    nsresult SetCurScrollPosEx(int32_t curHorizontalPos, int32_t curVerticalPos);

    // Override the parent setter from nsDocLoader
    virtual nsresult SetDocLoaderParent(nsDocLoader * aLoader) MOZ_OVERRIDE;

    void ClearFrameHistory(nsISHEntry* aEntry);

    /**
     * Initializes mTiming if it isn't yet.
     * After calling this, mTiming is non-null.
     */
    void MaybeInitTiming();

    // Event type dispatched by RestorePresentation
    class RestorePresentationEvent : public nsRunnable {
    public:
        NS_DECL_NSIRUNNABLE
        explicit RestorePresentationEvent(nsDocShell *ds) : mDocShell(ds) {}
        void Revoke() { mDocShell = nullptr; }
    private:
        nsRefPtr<nsDocShell> mDocShell;
    };

    bool JustStartedNetworkLoad();

    nsresult CreatePrincipalFromReferrer(nsIURI*        aReferrer,
                                         nsIPrincipal** outPrincipal);

    enum FrameType {
        eFrameTypeRegular,
        eFrameTypeBrowser,
        eFrameTypeApp
    };

    static const nsCString FrameTypeToString(FrameType aFrameType)
    {
      switch (aFrameType) {
      case FrameType::eFrameTypeApp:
        return NS_LITERAL_CSTRING("app");
      case FrameType::eFrameTypeBrowser:
        return NS_LITERAL_CSTRING("browser");
      case FrameType::eFrameTypeRegular:
        return NS_LITERAL_CSTRING("regular");
      default:
        NS_ERROR("Unknown frame type");
        return EmptyCString();
      }
    }

    FrameType GetInheritedFrameType();

    bool HasUnloadedParent();

    // Dimensions of the docshell
    nsIntRect                  mBounds;
    nsString                   mName;
    nsString                   mTitle;

    /**
     * Content-Type Hint of the most-recently initiated load. Used for
     * session history entries.
     */
    nsCString                  mContentTypeHint;
    nsIntPoint                 mDefaultScrollbarPref; // persistent across doc loads

    nsCOMPtr<nsISupportsArray> mRefreshURIList;
    nsCOMPtr<nsISupportsArray> mSavedRefreshURIList;
    nsRefPtr<nsDSURIContentListener> mContentListener;
    nsCOMPtr<nsIContentViewer> mContentViewer;
    nsCOMPtr<nsIWidget>        mParentWidget;

    // mCurrentURI should be marked immutable on set if possible.
    nsCOMPtr<nsIURI>           mCurrentURI;
    nsCOMPtr<nsIURI>           mReferrerURI;
    uint32_t                   mReferrerPolicy;
    nsRefPtr<nsGlobalWindow>   mScriptGlobal;
    nsCOMPtr<nsISHistory>      mSessionHistory;
    nsCOMPtr<nsIGlobalHistory2> mGlobalHistory;
    nsCOMPtr<nsIWebBrowserFind> mFind;
    nsCOMPtr<nsICommandManager> mCommandManager;
    // Reference to the SHEntry for this docshell until the page is destroyed.
    // Somebody give me better name
    nsCOMPtr<nsISHEntry>       mOSHE;
    // Reference to the SHEntry for this docshell until the page is loaded
    // Somebody give me better name.
    // If mLSHE is non-null, non-pushState subframe loads don't create separate
    // root history entries. That is, frames loaded during the parent page
    // load don't generate history entries the way frame navigation after the
    // parent has loaded does. (This isn't the only purpose of mLSHE.)
    nsCOMPtr<nsISHEntry>       mLSHE;

    // Holds a weak pointer to a RestorePresentationEvent object if any that
    // holds a weak pointer back to us.  We use this pointer to possibly revoke
    // the event whenever necessary.
    nsRevocableEventPtr<RestorePresentationEvent> mRestorePresentationEvent;

    // Editor data, if this document is designMode or contentEditable.
    nsAutoPtr<nsDocShellEditorData> mEditorData;

    // Transferable hooks/callbacks
    nsCOMPtr<nsIClipboardDragDropHookList> mTransferableHookData;

    // Secure browser UI object
    nsCOMPtr<nsISecureBrowserUI> mSecurityUI;

    // The URI we're currently loading.  This is only relevant during the
    // firing of a pagehide/unload.  The caller of FirePageHideNotification()
    // is responsible for setting it and unsetting it.  It may be null if the
    // pagehide/unload is happening for some reason other than just loading a
    // new URI.
    nsCOMPtr<nsIURI>           mLoadingURI;

    // Set in LoadErrorPage from the method argument and used later
    // in CreateContentViewer. We have to delay an shistory entry creation
    // for which these objects are needed.
    nsCOMPtr<nsIURI>           mFailedURI;
    nsCOMPtr<nsIChannel>       mFailedChannel;
    uint32_t                   mFailedLoadType;

    // window.location.searchParams is updated in sync with this object.
    nsRefPtr<mozilla::dom::URLSearchParams> mURLSearchParams;

    // Set in DoURILoad when either the LOAD_RELOAD_ALLOW_MIXED_CONTENT flag or
    // the LOAD_NORMAL_ALLOW_MIXED_CONTENT flag is set.
    // Checked in nsMixedContentBlocker, to see if the channels match.
    nsCOMPtr<nsIChannel>       mMixedContentChannel;

    // WEAK REFERENCES BELOW HERE.
    // Note these are intentionally not addrefd.  Doing so will create a cycle.
    // For that reasons don't use nsCOMPtr.

    nsIDocShellTreeOwner *     mTreeOwner; // Weak Reference
    mozilla::dom::EventTarget* mChromeEventHandler; //Weak Reference

    eCharsetReloadState        mCharsetReloadState;

    // Offset in the parent's child list.
    // -1 if the docshell is added dynamically to the parent shell.
    uint32_t                   mChildOffset;
    uint32_t                   mBusyFlags;
    uint32_t                   mAppType;
    uint32_t                   mLoadType;

    int32_t                    mMarginWidth;
    int32_t                    mMarginHeight;

    // This can either be a content docshell or a chrome docshell.  After
    // Create() is called, the type is not expected to change.
    int32_t                    mItemType;

    // Index into the SHTransaction list, indicating the previous and current
    // transaction at the time that this DocShell begins to load
    int32_t                    mPreviousTransIndex;
    int32_t                    mLoadedTransIndex;

    uint32_t                   mSandboxFlags;
    nsWeakPtr                  mOnePermittedSandboxedNavigator;

    // mFullscreenAllowed stores how we determine whether fullscreen is allowed
    // when GetFullscreenAllowed() is called. Fullscreen is allowed in a
    // docshell when all containing iframes have the allowfullscreen
    // attribute set to true. When mFullscreenAllowed is CHECK_ATTRIBUTES
    // we check this docshell's containing frame for the allowfullscreen
    // attribute, and recurse onto the parent docshell to ensure all containing
    // frames also have the allowfullscreen attribute. If we find an ancestor
    // docshell with mFullscreenAllowed not equal to CHECK_ATTRIBUTES, we've
    // reached a content boundary, and mFullscreenAllowed denotes whether the
    // parent across the content boundary has allowfullscreen=true in all its
    // containing iframes. mFullscreenAllowed defaults to CHECK_ATTRIBUTES and
    // is set otherwise when docshells which are content boundaries are created.
    enum FullscreenAllowedState {
        CHECK_ATTRIBUTES,
        PARENT_ALLOWS,
        PARENT_PROHIBITS
    };
    FullscreenAllowedState     mFullscreenAllowed;

    // Cached value of the "browser.xul.error_pages.enabled" preference.
    static bool                sUseErrorPages;

    bool                       mCreated;
    bool                       mAllowSubframes;
    bool                       mAllowPlugins;
    bool                       mAllowJavascript;
    bool                       mAllowMetaRedirects;
    bool                       mAllowImages;
    bool                       mAllowMedia;
    bool                       mAllowDNSPrefetch;
    bool                       mAllowWindowControl;
    bool                       mAllowContentRetargeting;
    bool                       mCreatingDocument; // (should be) debugging only
    bool                       mUseErrorPages;
    bool                       mObserveErrorPages;
    bool                       mAllowAuth;
    bool                       mAllowKeywordFixup;
    bool                       mIsOffScreenBrowser;
    bool                       mIsActive;
    bool                       mIsPrerendered;
    bool                       mIsAppTab;
    bool                       mUseGlobalHistory;
    bool                       mInPrivateBrowsing;
    bool                       mUseRemoteTabs;
    bool                       mDeviceSizeIsPageSize;

    // Because scriptability depends on the mAllowJavascript values of our
    // ancestors, we cache the effective scriptability and recompute it when
    // it might have changed;
    bool                       mCanExecuteScripts;
    void RecomputeCanExecuteScripts();

    // This boolean is set to true right before we fire pagehide and generally
    // unset when we embed a new content viewer.  While it's true no navigation
    // is allowed in this docshell.
    bool                       mFiredUnloadEvent;

    // this flag is for bug #21358. a docshell may load many urls
    // which don't result in new documents being created (i.e. a new
    // content viewer) we want to make sure we don't call a on load
    // event more than once for a given content viewer.
    bool                       mEODForCurrentDocument;
    bool                       mURIResultedInDocument;

    bool                       mIsBeingDestroyed;

    bool                       mIsExecutingOnLoadHandler;

    // Indicates that a DocShell in this "docshell tree" is printing
    bool                       mIsPrintingOrPP;

    // Indicates to CreateContentViewer() that it is safe to cache the old
    // presentation of the page, and to SetupNewViewer() that the old viewer
    // should be passed a SHEntry to save itself into.
    bool                       mSavingOldViewer;
    
    // @see nsIDocShellHistory::createdDynamically
    bool                       mDynamicallyCreated;
#ifdef DEBUG
    bool                       mInEnsureScriptEnv;
#endif
    bool                       mAffectPrivateSessionLifetime;
    bool                       mInvisible;
    bool                       mHasLoadedNonBlankURI;
    uint64_t                   mHistoryID;
    uint32_t                   mDefaultLoadFlags;

    static nsIURIFixup *sURIFixup;

    nsRefPtr<nsDOMNavigationTiming> mTiming;

    // This flag means that mTiming has been initialized but nulled out.
    // We will check the innerWin's timing before creating a new one
    // in MaybeInitTiming()
    bool                            mBlankTiming;

    // Are we a regular frame, a browser frame, or an app frame?
    FrameType mFrameType;

    // We only expect mOwnOrContainingAppId to be something other than
    // UNKNOWN_APP_ID if mFrameType != eFrameTypeRegular.  For vanilla iframes
    // inside an app, we'll retrieve the containing app-id by walking up the
    // docshell hierarchy.
    //
    // (This needs to be the docshell's own /or containing/ app id because the
    // containing app frame might be in another process, in which case we won't
    // find it by walking up the docshell hierarchy.)
    uint32_t mOwnOrContainingAppId;

private:
    nsCString         mForcedCharset;
    nsCString         mParentCharset;
    int32_t           mParentCharsetSource;
    nsCOMPtr<nsIPrincipal> mParentCharsetPrincipal;
    nsTObserverArray<nsWeakPtr> mPrivacyObservers;
    nsTObserverArray<nsWeakPtr> mReflowObservers;
    nsTObserverArray<nsWeakPtr> mScrollObservers;
    nsCString         mOriginalUriString;
    nsWeakPtr mOpener;
    nsWeakPtr mOpenedRemote;

    // A depth count of how many times NotifyRunToCompletionStart
    // has been called without a matching NotifyRunToCompletionStop.
    uint32_t          mJSRunToCompletionDepth;

    // True if recording profiles.
    bool mProfileTimelineRecording;

    nsTArray<TimelineMarker*> mProfileTimelineMarkers;

    // Get rid of all the timeline markers accumulated so far
    void ClearProfileTimelineMarkers();

    // Separate function to do the actual name (i.e. not _top, _self etc.)
    // searching for FindItemWithName.
    nsresult DoFindItemWithName(const char16_t* aName,
                                nsISupports* aRequestor,
                                nsIDocShellTreeItem* aOriginalRequestor,
                                nsIDocShellTreeItem** _retval);

    // Notify consumers of a search being loaded through the observer service:
    void MaybeNotifyKeywordSearchLoading(const nsString &aProvider, const nsString &aKeyword);

#ifdef DEBUG
    // We're counting the number of |nsDocShells| to help find leaks
    static unsigned long gNumberOfDocShells;
#endif /* DEBUG */

public:
    class InterfaceRequestorProxy : public nsIInterfaceRequestor {
    public:
        explicit InterfaceRequestorProxy(nsIInterfaceRequestor* p);
        NS_DECL_THREADSAFE_ISUPPORTS
        NS_DECL_NSIINTERFACEREQUESTOR
 
    protected:
        virtual ~InterfaceRequestorProxy();
        InterfaceRequestorProxy() {}
        nsWeakPtr mWeakPtr;
    };
};

#endif /* nsDocShell_h__ */