Bug 618249: Default remote-browser to synchronous scrolling, and let users change that. r=tn sr=roc a=a

content/base/public/nsIFrameLoader.idl

@@ -176,3 +176,25 @@ interface nsIFrameLoaderOwner : nsISupports
    */
   void swapFrameLoaders(in nsIFrameLoaderOwner aOtherOwner);
 };
+
+/** Please merge me into something else after 2.0 branches. */
+[scriptable, uuid(e3e2d3f8-1397-4984-abb3-435c29a1ca55)]
+interface nsIFrameLoader_MOZILLA_2_0_BRANCH : nsISupports
+{
+  /** 
+   * The default rendering mode is synchronous scrolling.  In this
+   * mode, it's an error to try to set a target viewport.
+   */
+  const unsigned long RENDER_MODE_DEFAULT        = 0x00000000;
+  /**
+   * When asynchronous scrolling is enabled, a target viewport can be
+   * set to transform content pixels wrt its CSS viewport.
+   *
+   * NB: when async scrolling is enabled, it's the *user's*
+   * responsibility to update the target scroll offset.  In effect,
+   * the platform hands over control of scroll offset to the user.
+   */
+  const unsigned long RENDER_MODE_ASYNC_SCROLL   = 0x00000001;
+
+  attribute unsigned long renderMode;
+};

content/base/src/nsFrameLoader.cpp

@@ -171,12 +171,13 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsFrameLoader)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(mChildMessageManager)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
-NS_IMPL_CYCLE_COLLECTING_ADDREF(nsFrameLoader)
-NS_IMPL_CYCLE_COLLECTING_RELEASE(nsFrameLoader)
+NS_IMPL_CYCLE_COLLECTING_ADDREF_AMBIGUOUS(nsFrameLoader, nsIFrameLoader)
+NS_IMPL_CYCLE_COLLECTING_RELEASE_AMBIGUOUS(nsFrameLoader, nsIFrameLoader)
 
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsFrameLoader)
   NS_INTERFACE_MAP_ENTRY(nsIFrameLoader)
-  NS_INTERFACE_MAP_ENTRY(nsISupports)
+  NS_INTERFACE_MAP_ENTRY(nsIFrameLoader_MOZILLA_2_0_BRANCH)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIFrameLoader)
 NS_INTERFACE_MAP_END
 
 nsFrameLoader*
@@ -1544,12 +1545,34 @@ nsFrameLoader::GetViewportScrollY(float* aViewportScrollY)
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsFrameLoader::GetRenderMode(PRUint32* aRenderMode)
+{
+  *aRenderMode = mViewportConfig.mRenderMode;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsFrameLoader::SetRenderMode(PRUint32 aRenderMode)
+{
+  ViewportConfig config(mViewportConfig);
+  config.mRenderMode = aRenderMode;
+  return UpdateViewportConfig(config);
+}
+
 nsresult
 nsFrameLoader::UpdateViewportConfig(const ViewportConfig& aNewConfig)
 {
   if (aNewConfig == mViewportConfig) {
     return NS_OK;
+  } else if (!mViewportConfig.AsyncScrollEnabled() &&
+             !aNewConfig.AsyncScrollEnabled()) {
+    // The target viewport can't be set in synchronous mode
+    return NS_ERROR_NOT_AVAILABLE;
   }
+  // XXX if we go from disabled->enabled, should we clear out the old
+  // config?  Or what?
+
   mViewportConfig = aNewConfig;
 
   // Viewport changed.  Try to locate our subdoc frame and invalidate

content/base/src/nsFrameLoader.h

@@ -80,7 +80,8 @@ class QX11EmbedContainer;
 #endif
 #endif
 
-class nsFrameLoader : public nsIFrameLoader
+class nsFrameLoader : public nsIFrameLoader,
+                      public nsIFrameLoader_MOZILLA_2_0_BRANCH
 {
   friend class AutoResetInShow;
 #ifdef MOZ_IPC
@@ -121,7 +122,8 @@ public:
    */
   struct ViewportConfig {
     ViewportConfig()
-      : mScrollOffset(0, 0)
+      : mRenderMode(nsIFrameLoader_MOZILLA_2_0_BRANCH::RENDER_MODE_DEFAULT)
+      , mScrollOffset(0, 0)
       , mXScale(1.0)
       , mYScale(1.0)
     {}
@@ -130,11 +132,21 @@ public:
 
     PRBool operator==(const ViewportConfig& aOther) const
     {
-      return (mScrollOffset == aOther.mScrollOffset &&
+      return (mRenderMode == aOther.mRenderMode &&
+              mScrollOffset == aOther.mScrollOffset &&
               mXScale == aOther.mXScale &&
               mYScale == aOther.mYScale);
     }
 
+    PRBool AsyncScrollEnabled() const
+    {
+      return !!(mRenderMode & RENDER_MODE_ASYNC_SCROLL);
+    }
+
+    // See nsIFrameLoader.idl.  Short story, if !(mRenderMode &
+    // RENDER_MODE_ASYNC_SCROLL), all the fields below are ignored in
+    // favor of what content tells.
+    PRUint32 mRenderMode;
     // This is the scroll offset the <browser> user wishes or expects
     // its enclosed content document to have.  "Scroll offset" here
     // means the document pixel at pixel (0,0) within the CSS
@@ -162,8 +174,9 @@ public:
   static nsFrameLoader* Create(nsIContent* aOwner, PRBool aNetworkCreated);
 
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
-  NS_DECL_CYCLE_COLLECTION_CLASS(nsFrameLoader)
+  NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(nsFrameLoader, nsIFrameLoader)
   NS_DECL_NSIFRAMELOADER
+  NS_DECL_NSIFRAMELOADER_MOZILLA_2_0_BRANCH
   NS_HIDDEN_(nsresult) CheckForRecursiveLoad(nsIURI* aURI);
   nsresult ReallyStartLoading();
   void Finalize();

content/base/src/nsObjectLoadingContent.cpp

@@ -1524,7 +1524,7 @@ nsObjectLoadingContent::RemovedFromDocument()
 void
 nsObjectLoadingContent::Traverse(nsCycleCollectionTraversalCallback &cb)
 {
-  cb.NoteXPCOMChild(mFrameLoader);
+  cb.NoteXPCOMChild(static_cast<nsIFrameLoader*>(mFrameLoader));
 }
 
 // <private>

content/canvas/src/nsCanvasRenderingContext2D.cpp

@@ -3692,7 +3692,7 @@ nsCanvasRenderingContext2D::AsyncDrawXULElement(nsIDOMXULElement* aElem, float a
     if (!loaderOwner)
         return NS_ERROR_FAILURE;
 
-    nsCOMPtr<nsFrameLoader> frameloader = loaderOwner->GetFrameLoader();
+    nsRefPtr<nsFrameLoader> frameloader = loaderOwner->GetFrameLoader();
     if (!frameloader)
         return NS_ERROR_FAILURE;
 

content/html/content/src/nsGenericHTMLElement.cpp

@@ -3052,7 +3052,7 @@ nsGenericHTMLFrameElement::~nsGenericHTMLFrameElement()
 NS_IMPL_CYCLE_COLLECTION_CLASS(nsGenericHTMLFrameElement)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(nsGenericHTMLFrameElement,
                                                   nsGenericHTMLElement)
-  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(mFrameLoader)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR_AMBIGUOUS(mFrameLoader, nsIFrameLoader)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_INTERFACE_TABLE_HEAD(nsGenericHTMLFrameElement)

layout/ipc/RenderFrameParent.cpp

@@ -97,20 +97,26 @@ ComputeShadowTreeTransform(nsIFrame* aContainerFrame,
      aContainerFrame->GetContentRect().TopLeft());
   *aShadowTranslation = frameOffset.ToNearestPixels(auPerDevPixel);
 
-  // |aMetrics.mViewportScrollOffset| was the content document's
-  // scroll offset when it was painted (the document pixel at CSS
-  // viewport (0,0)).  |aConfig.mScrollOffset| is what our user
-  // expects, or wants, the content-document scroll offset to be.  So
-  // we set a compensating translation that moves the content document
-  // pixels to where the user wants them to be.
-  nsIntPoint scrollCompensation =
-    (aConfig.mScrollOffset.ToNearestPixels(auPerDevPixel));
-  scrollCompensation.x -= aMetrics.mViewportScrollOffset.x * aConfig.mXScale;
-  scrollCompensation.y -= aMetrics.mViewportScrollOffset.y * aConfig.mYScale;
-  *aShadowTranslation -= scrollCompensation;
+  if (aConfig.AsyncScrollEnabled()) {
+    // |aMetrics.mViewportScrollOffset| was the content document's
+    // scroll offset when it was painted (the document pixel at CSS
+    // viewport (0,0)).  |aConfig.mScrollOffset| is what our user
+    // expects, or wants, the content-document scroll offset to be.  So
+    // we set a compensating translation that moves the content document
+    // pixels to where the user wants them to be.
+    nsIntPoint scrollCompensation =
+      (aConfig.mScrollOffset.ToNearestPixels(auPerDevPixel));
+    scrollCompensation.x -= aMetrics.mViewportScrollOffset.x * aConfig.mXScale;
+    scrollCompensation.y -= aMetrics.mViewportScrollOffset.y * aConfig.mYScale;
+    *aShadowTranslation -= scrollCompensation;
 
-  *aShadowXScale = aConfig.mXScale;
-  *aShadowYScale = aConfig.mYScale;
+    *aShadowXScale = aConfig.mXScale;
+    *aShadowYScale = aConfig.mYScale;
+  } else {
+    *aShadowXScale = 1;
+    *aShadowYScale = 1;
+  }
+           
 }
 
 static void

layout/ipc/test-ipcbrowser-chrome.js

@@ -1,4 +1,5 @@
 function init() {
+    enableAsyncScrolling();
     messageManager.loadFrameScript(
         "chrome://global/content/test-ipcbrowser-content.js", true
     );
@@ -13,6 +14,12 @@ function frameLoader() {
                     .frameLoader;
 }
 
+function enableAsyncScrolling() {
+    var i = Components.interfaces.nsIFrameLoader_MOZILLA_2_0_BRANCH;
+    var enabler = frameLoader().QueryInterface(i);
+    enabler.renderMode = i.RENDER_MODE_ASYNC_SCROLL;
+}
+
 // Functions affecting the content window.
 
 function loadURL(url) {