Bug 1008455 - Avoid loading the xul.css UA style sheet when possible. r=bz CLOSED TREE

--HG--
rename : toolkit/content/xul.css => toolkit/content/minimal-xul.css

content/base/public/nsIContent.h

@@ -70,9 +70,11 @@ public:
    * appended to a parent, this will be called after the node has been added to
    * the parent's child list and before nsIDocumentObserver notifications for
    * the addition are dispatched.
-   * @param aDocument The new document for the content node.  Must match the
-   *                  current document of aParent, if aParent is not null.
-   *                  May not be null if aParent is null.
+   * @param aDocument The new document for the content node.  May not be null
+   *                  if aParent is null.  Must match the current document of
+   *                  aParent, if aParent is not null (note that
+   *                  aParent->GetCurrentDoc() can be null, in which case this
+   *                  must also be null).
    * @param aParent The new parent for the content node.  May be null if the
    *                node is being bound as a direct child of the document.
    * @param aBindingParent The new binding parent for the content node.

content/base/public/nsIDocument.h

@@ -1213,14 +1213,32 @@ public:
                                  nsAString& aEncoding,
                                  nsAString& Standalone) = 0;
 
+  /**
+   * Returns true if this is what HTML 5 calls an "HTML document" (for example
+   * regular HTML document with Content-Type "text/html", image documents and
+   * media documents).  Returns false for XHTML and any other documents parsed
+   * by the XML parser.
+   */
   bool IsHTML() const
   {
     return mIsRegularHTML;
   }
+  bool IsXML() const
+  {
+    return !IsHTML();
+  }
   bool IsXUL() const
   {
     return mIsXUL;
   }
+  bool IsUnstyledDocument()
+  {
+    return IsLoadedAsData() || IsLoadedAsInteractiveData();
+  }
+  bool LoadsFullXULStyleSheetUpFront()
+  {
+    return IsXUL() || AllowXULXBL();
+  }
 
   virtual bool IsScriptEnabled() = 0;
 

content/svg/document/src/SVGDocument.h

@@ -17,6 +17,11 @@ namespace dom {
 class SVGDocument MOZ_FINAL : public XMLDocument
 {
 public:
+  SVGDocument()
+    : XMLDocument("image/svg+xml")
+  {
+  }
+
   virtual nsresult Clone(nsINodeInfo *aNodeInfo, nsINode **aResult) const MOZ_OVERRIDE;
 
   // WebIDL API

content/xul/content/src/nsXULElement.cpp

@@ -33,6 +33,7 @@
 #include "nsIDOMElementCSSInlineStyle.h"
 #include "nsIDOMXULSelectCntrlItemEl.h"
 #include "nsIDocument.h"
+#include "nsLayoutStylesheetCache.h"
 #include "mozilla/EventListenerManager.h"
 #include "mozilla/EventStateManager.h"
 #include "mozilla/EventStates.h"
@@ -729,6 +730,68 @@ nsXULElement::UpdateEditableState(bool aNotify)
     UpdateState(aNotify);
 }
 
+/**
+ * Returns true if the user-agent style sheet rules for this XUL element are
+ * in minimal-xul.css instead of xul.css.
+ */
+static inline bool XULElementsRulesInMinimalXULSheet(nsIAtom* aTag)
+{
+  return // scrollbar parts:
+         aTag == nsGkAtoms::scrollbar ||
+         aTag == nsGkAtoms::scrollbarbutton ||
+         aTag == nsGkAtoms::scrollcorner ||
+         aTag == nsGkAtoms::slider ||
+         aTag == nsGkAtoms::thumb ||
+         aTag == nsGkAtoms::scale ||
+         // other
+         aTag == nsGkAtoms::resizer ||
+         aTag == nsGkAtoms::label ||
+         aTag == nsGkAtoms::videocontrols;
+}
+
+#ifdef DEBUG
+/**
+ * Returns true if aElement is a XUL element created by the video controls
+ * binding. HTML <video> and <audio> bindings pull in this binding. This
+ * binding creates lots of different types of XUL elements.
+ */
+static inline bool
+IsInVideoControls(nsXULElement* aElement)
+{
+  nsIContent* ancestor = aElement->GetParent();
+  while (ancestor) {
+    if (ancestor->NodeInfo()->Equals(nsGkAtoms::videocontrols, kNameSpaceID_XUL)) {
+      return true;
+    }
+    ancestor = ancestor->GetParent();
+  }
+  return false;
+}
+
+/**
+ * Returns true if aElement is an element created by the <binding
+ * id="feedreaderUI"> binding or one of the bindings bound to such an element.
+ * element in one of the binding for such an element. Only
+ * subscribe.xhtml#feedSubscribeLine pulls in the feedreaderUI binding. This
+ * binding creates lots of different types of XUL elements.
+ */
+bool
+IsInFeedSubscribeLine(nsXULElement* aElement)
+{
+  nsIContent* bindingParent = aElement->GetBindingParent();
+  if (bindingParent) {
+    while (bindingParent->GetBindingParent()) {
+      bindingParent = bindingParent->GetBindingParent();
+    }
+    nsIAtom* idAtom = bindingParent->GetID();
+    if (idAtom && idAtom->Equals(NS_LITERAL_STRING("feedSubscribeLine"))) {
+      return true;
+    }
+  }
+  return false;
+}
+#endif
+
 nsresult
 nsXULElement::BindToTree(nsIDocument* aDocument,
                          nsIContent* aParent,
@@ -740,6 +803,38 @@ nsXULElement::BindToTree(nsIDocument* aDocument,
                                             aCompileEventHandlers);
   NS_ENSURE_SUCCESS(rv, rv);
 
+  if (aDocument &&
+      !aDocument->LoadsFullXULStyleSheetUpFront() &&
+      !aDocument->IsUnstyledDocument()) {
+
+    // To save CPU cycles and memory, non-XUL documents only load the user
+    // agent style sheet rules for a minimal set of XUL elements such as
+    // 'scrollbar' that may be created implicitly for their content (those
+    // rules being in minimal-xul.css).  This is where we make sure that all
+    // the other XUL UA style sheet rules (xul.css) have been loaded if the
+    // minimal set is not sufficient.
+    //
+    // We do this during binding, not element construction, because elements
+    // can be moved from the document that creates them to another document.
+
+    if (!XULElementsRulesInMinimalXULSheet(Tag())) {
+      aDocument->EnsureOnDemandBuiltInUASheet(nsLayoutStylesheetCache::XULSheet());
+      // To keep memory usage down it is important that we try and avoid
+      // pulling xul.css into non-XUL documents. That should be very rare, and
+      // for HTML we currently should only pull it in if the document contains
+      // an <audio> or <video> element. This assertion is here to make sure
+      // that we don't fail to notice if a change to bindings causes us to
+      // start pulling in xul.css much more frequently. If this assertion
+      // fails then we need to figure out why, and how we can continue to avoid
+      // pulling in xul.css.
+      // Note that add-ons may introduce bindings that cause this assertion to
+      // fire.
+      NS_ASSERTION(IsInVideoControls(this) ||
+                   IsInFeedSubscribeLine(this),
+                   "Unexpected XUL element in non-XUL doc");
+    }
+  }
+
   if (aDocument) {
       NS_ASSERTION(!nsContentUtils::IsSafeToRunScript(),
                    "Missing a script blocker!");

layout/base/nsDocumentViewer.cpp

@@ -2280,6 +2280,20 @@ nsDocumentViewer::CreateStyleSet(nsIDocument* aDocument,
   // after the html.css and so forth that the UA sheet imports).
   styleSet->PrependStyleSheet(nsStyleSet::eAgentSheet, quirkClone);
   styleSet->SetQuirkStyleSheet(quirkClone);
+  if (aDocument->LoadsFullXULStyleSheetUpFront()) {
+    // nsXULElement::BindToTree loads xul.css on-demand if we don't load it
+    // up-front here.
+    sheet = nsLayoutStylesheetCache::XULSheet();
+    if (sheet) {
+      styleSet->PrependStyleSheet(nsStyleSet::eAgentSheet, sheet);
+    }
+  }
+  sheet = nsLayoutStylesheetCache::MinimalXULSheet();
+  if (sheet) {
+    // Load the minimal XUL rules for scrollbars and a few other XUL things
+    // that non-XUL (typically HTML) documents commonly use.
+    styleSet->PrependStyleSheet(nsStyleSet::eAgentSheet, sheet);
+  }
   styleSet->PrependStyleSheet(nsStyleSet::eAgentSheet,
                               nsLayoutStylesheetCache::UASheet());
 

layout/style/nsLayoutStylesheetCache.cpp

@@ -148,6 +148,26 @@ nsLayoutStylesheetCache::UASheet()
   return gStyleCache->mUASheet;
 }
 
+nsCSSStyleSheet*
+nsLayoutStylesheetCache::MinimalXULSheet()
+{
+  EnsureGlobal();
+  if (!gStyleCache)
+    return nullptr;
+
+  return gStyleCache->mMinimalXULSheet;
+}
+
+nsCSSStyleSheet*
+nsLayoutStylesheetCache::XULSheet()
+{
+  EnsureGlobal();
+  if (!gStyleCache)
+    return nullptr;
+
+  return gStyleCache->mXULSheet;
+}
+
 nsCSSStyleSheet*
 nsLayoutStylesheetCache::QuirkSheet()
 {
@@ -230,6 +250,8 @@ nsLayoutStylesheetCache::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf
   MEASURE(mUserContentSheet);
   MEASURE(mUserChromeSheet);
   MEASURE(mUASheet);
+  MEASURE(mMinimalXULSheet);
+  MEASURE(mXULSheet);
   MEASURE(mQuirkSheet);
   MEASURE(mFullScreenOverrideSheet);
   MEASURE(mSVGSheet);
@@ -268,6 +290,18 @@ nsLayoutStylesheetCache::nsLayoutStylesheetCache()
   }
   NS_ASSERTION(mUASheet, "Could not load ua.css");
 
+  NS_NewURI(getter_AddRefs(uri), "chrome://global/content/minimal-xul.css");
+  if (uri) {
+    LoadSheet(uri, mMinimalXULSheet, true);
+  }
+  NS_ASSERTION(mMinimalXULSheet, "Could not load minimal-xul.css");
+
+  NS_NewURI(getter_AddRefs(uri), "chrome://global/content/xul.css");
+  if (uri) {
+    LoadSheet(uri, mXULSheet, true);
+  }
+  NS_ASSERTION(mXULSheet, "Could not load xul.css");
+
   NS_NewURI(getter_AddRefs(uri), "resource://gre-resources/quirk.css");
   if (uri) {
     LoadSheet(uri, mQuirkSheet, true);

layout/style/nsLayoutStylesheetCache.h

@@ -39,6 +39,8 @@ class nsLayoutStylesheetCache MOZ_FINAL
   static nsCSSStyleSheet* UserContentSheet();
   static nsCSSStyleSheet* UserChromeSheet();
   static nsCSSStyleSheet* UASheet();
+  static nsCSSStyleSheet* MinimalXULSheet();
+  static nsCSSStyleSheet* XULSheet();
   static nsCSSStyleSheet* QuirkSheet();
   static nsCSSStyleSheet* FullScreenOverrideSheet();
   static nsCSSStyleSheet* SVGSheet();
@@ -67,6 +69,8 @@ private:
   nsRefPtr<nsCSSStyleSheet> mUserContentSheet;
   nsRefPtr<nsCSSStyleSheet> mUserChromeSheet;
   nsRefPtr<nsCSSStyleSheet> mUASheet;
+  nsRefPtr<nsCSSStyleSheet> mMinimalXULSheet;
+  nsRefPtr<nsCSSStyleSheet> mXULSheet;
   nsRefPtr<nsCSSStyleSheet> mQuirkSheet;
   nsRefPtr<nsCSSStyleSheet> mFullScreenOverrideSheet;
   nsRefPtr<nsCSSStyleSheet> mSVGSheet;

layout/style/ua.css

@@ -3,7 +3,6 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 @import url(resource://gre-resources/html.css);
-@import url(chrome://global/content/xul.css);
 
 @namespace parsererror url(http://www.mozilla.org/newlayout/xml/parsererror.xml);
 @namespace xul url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);

toolkit/content/jar.mn

@@ -7,6 +7,7 @@ toolkit.jar:
 %  override chrome://global/content/nsTransferable.js chrome://global/content/nsDragAndDrop.js
 *  content/global/license.html                (license.html)
    content/global/XPCNativeWrapper.js         (XPCNativeWrapper.js)
+*  content/global/minimal-xul.css             (minimal-xul.css)
 *  content/global/xul.css                     (xul.css)
    content/global/textbox.css                 (textbox.css)
    content/global/menulist.css                (menulist.css)

toolkit/content/minimal-xul.css

@@ -0,0 +1,133 @@
+/* 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/. */
+
+/**
+ * This file should only contain a minimal set of rules for the XUL elements
+ * that may be implicitly created as part of HTML/SVG documents (e.g.
+ * scrollbars).  Rules for everything else related to XUL can be found in
+ * xul.css.  (This split of the XUL rules is to minimize memory use and improve
+ * performance in HTML/SVG documents.)
+ *
+ * This file should also not contain any app specific styling.  Defaults for
+ * widgets of a particular application should be in that application's style
+ * sheet.  For example style definitions for navigator can be found in
+ * navigator.css.
+ *
+ * THIS FILE IS LOCKED DOWN.  YOU ARE NOT ALLOWED TO MODIFY IT WITHOUT FIRST
+ * HAVING YOUR CHANGES REVIEWED BY enndeakin@gmail.com
+ */
+
+@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* set default namespace to XUL */
+@namespace html url("http://www.w3.org/1999/xhtml"); /* namespace for HTML elements */
+
+* {
+  -moz-user-focus: ignore;
+  -moz-user-select: none;
+  display: -moz-box;
+  box-sizing: border-box;
+}
+
+:root {
+  text-rendering: optimizeLegibility;
+  -moz-binding: url("chrome://global/content/bindings/general.xml#root-element");
+  -moz-control-character-visibility: visible;
+}
+
+:root:-moz-locale-dir(rtl) {
+  direction: rtl;
+}
+
+/* hide the content and destroy the frame */
+[hidden="true"] {
+  display: none;
+}
+
+/* hide the content, but don't destroy the frames */
+[collapsed="true"],
+[moz-collapsed="true"] {
+  visibility: collapse;
+}
+
+/********** label **********/
+
+description {
+  -moz-binding: url("chrome://global/content/bindings/text.xml#text-base");
+}
+
+label {
+  -moz-binding: url("chrome://global/content/bindings/text.xml#text-label");
+}
+
+label.text-link, label[onclick] {
+  -moz-binding: url("chrome://global/content/bindings/text.xml#text-link");
+  -moz-user-focus: normal;
+}
+
+label[control], label.radio-label, label.checkbox-label, label.toolbarbutton-multiline-text {
+  -moz-binding: url("chrome://global/content/bindings/text.xml#label-control");
+}
+
+html|span.accesskey {
+  text-decoration: underline;
+}
+
+/********** resizer **********/
+
+resizer {
+  -moz-binding: url("chrome://global/content/bindings/resizer.xml#resizer");
+  position: relative;
+  z-index: 2147483647;
+}
+
+/********** scrollbar **********/
+
+/* Scrollbars are never flipped even if BiDI kicks in. */
+scrollbar[orient="horizontal"] {
+  direction: ltr;
+}
+
+thumb {
+  -moz-binding: url(chrome://global/content/bindings/scrollbar.xml#thumb);
+  display: -moz-box !important;
+}
+
+.scale-thumb {
+  -moz-binding: url(chrome://global/content/bindings/scale.xml#scalethumb);
+}
+
+scrollbar, scrollbarbutton, scrollcorner, slider, thumb, scale {
+  -moz-user-select: none;
+}
+
+scrollcorner {
+  display: -moz-box !important;
+}
+
+scrollcorner[hidden="true"] {
+  display: none !important;
+}
+
+scrollbar[value="hidden"] {
+  visibility: hidden;
+}
+
+scale {
+  -moz-binding: url(chrome://global/content/bindings/scale.xml#scale);
+}
+
+.scale-slider {
+  -moz-binding: url(chrome://global/content/bindings/scale.xml#scaleslider);
+  -moz-user-focus: normal;
+}
+
+scrollbarbutton[sbattr="scrollbar-up-top"]:not(:-moz-system-metric(scrollbar-start-backward)),
+scrollbarbutton[sbattr="scrollbar-down-top"]:not(:-moz-system-metric(scrollbar-start-forward)),
+scrollbarbutton[sbattr="scrollbar-up-bottom"]:not(:-moz-system-metric(scrollbar-end-backward)),
+scrollbarbutton[sbattr="scrollbar-down-bottom"]:not(:-moz-system-metric(scrollbar-end-forward)) {
+  display: none;
+}
+
+thumb[sbattr="scrollbar-thumb"]:-moz-system-metric(scrollbar-thumb-proportional) {
+  -moz-box-flex: 1;
+}

toolkit/content/xul.css

@@ -2,47 +2,27 @@
  * 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/. */
 
-/** this should only contain XUL dialog and document window widget defaults. Defaults for widgets of
-    a particular application should be in that application's style sheet.
-	For example style definitions for navigator can be found in navigator.css
-
-   THIS FILE IS LOCKED DOWN.  YOU ARE NOT ALLOWED TO MODIFY IT WITHOUT FIRST HAVING YOUR
-   CHANGES REVIEWED BY enndeakin@sympatico.ca
-**/
+/**
+ * A minimal set of rules for the XUL elements that may be implicitly created
+ * as part of HTML/SVG documents (e.g. scrollbars) can be found over in
+ * minimal-xul.css.  Rules for everything else related to XUL can be found in
+ * this file.  Make sure you choose the correct style sheet when adding new
+ * rules.  (This split of the XUL rules is to minimize memory use and improve
+ * performance in HTML/SVG documents.)
+ *
+ * This file should also not contain any app specific styling.  Defaults for
+ * widgets of a particular application should be in that application's style
+ * sheet.  For example, style definitions for navigator can be found in
+ * navigator.css.
+ *
+ * THIS FILE IS LOCKED DOWN.  YOU ARE NOT ALLOWED TO MODIFY IT WITHOUT FIRST
+ * HAVING YOUR CHANGES REVIEWED BY enndeakin@gmail.com
+ */
 
 @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* set default namespace to XUL */
 @namespace html url("http://www.w3.org/1999/xhtml"); /* namespace for HTML elements */
 @namespace xbl url("http://www.mozilla.org/xbl"); /* namespace for XBL elements */
 
-* {
-  -moz-user-focus: ignore;
-  -moz-user-select: none;
-  display: -moz-box;
-  box-sizing: border-box;
-}
-
-:root {
-  text-rendering: optimizeLegibility;
-  -moz-binding: url("chrome://global/content/bindings/general.xml#root-element");
-  -moz-control-character-visibility: visible;
-}
-
-:root:-moz-locale-dir(rtl) {
-  direction: rtl;
-}
-
-/* hide the content and destroy the frame */
-[hidden="true"] {
-  display: none;
-}
-
-/* hide the content, but don't destroy the frames */
-[collapsed="true"],
-[moz-collapsed="true"] {
-  visibility: collapse;
-}
-
-
 /* ::::::::::
    :: Rules for 'hiding' portions of the chrome for special
    :: kinds of windows (not JUST browser windows) with toolbars
@@ -749,29 +729,6 @@ progressmeter {
   -moz-box-direction: inherit;
 }
 
-/********** label **********/
-
-description {
-  -moz-binding: url("chrome://global/content/bindings/text.xml#text-base");
-}
-
-label {
-  -moz-binding: url("chrome://global/content/bindings/text.xml#text-label");
-}
-
-label.text-link, label[onclick] {
-  -moz-binding: url("chrome://global/content/bindings/text.xml#text-link");
-  -moz-user-focus: normal;
-}
-
-label[control], label.radio-label, label.checkbox-label, label.toolbarbutton-multiline-text {
-  -moz-binding: url("chrome://global/content/bindings/text.xml#label-control");
-}
-
-html|span.accesskey {
-  text-decoration: underline;
-}
-
 /********** textbox **********/
 
 textbox {
@@ -961,14 +918,6 @@ dropmarker {
   -moz-binding: url("chrome://global/content/bindings/general.xml#dropmarker");
 }
 
-/********** resizer **********/
-
-resizer {
-  -moz-binding: url("chrome://global/content/bindings/resizer.xml#resizer");
-  position: relative;
-  z-index: 2147483647;
-}
-
 /********** splitter **********/
 
 splitter {
@@ -987,58 +936,6 @@ grippy {
   -moz-box-ordinal-group: 2147483646;
 }
 
-/********** scrollbar **********/
-
-/* Scrollbars are never flipped even if BiDI kicks in. */
-scrollbar[orient="horizontal"] {
-  direction: ltr;
-}
-
-thumb {
-  -moz-binding: url(chrome://global/content/bindings/scrollbar.xml#thumb);
-  display: -moz-box !important;
-}
-
-.scale-thumb {
-  -moz-binding: url(chrome://global/content/bindings/scale.xml#scalethumb);
-}
-
-scrollbar, scrollbarbutton, scrollcorner, slider, thumb, scale {
-  -moz-user-select: none;
-}
-
-scrollcorner {
-  display: -moz-box !important;
-}
-
-scrollcorner[hidden="true"] {
-  display: none !important;
-}
-
-scrollbar[value="hidden"] {
-  visibility: hidden;
-}
-
-scale {
-  -moz-binding: url(chrome://global/content/bindings/scale.xml#scale);
-}
-
-.scale-slider {
-  -moz-binding: url(chrome://global/content/bindings/scale.xml#scaleslider);
-  -moz-user-focus: normal;
-}
-
-scrollbarbutton[sbattr="scrollbar-up-top"]:not(:-moz-system-metric(scrollbar-start-backward)),
-scrollbarbutton[sbattr="scrollbar-down-top"]:not(:-moz-system-metric(scrollbar-start-forward)),
-scrollbarbutton[sbattr="scrollbar-up-bottom"]:not(:-moz-system-metric(scrollbar-end-backward)),
-scrollbarbutton[sbattr="scrollbar-down-bottom"]:not(:-moz-system-metric(scrollbar-end-forward)) {
-  display: none;
-}
-
-thumb[sbattr="scrollbar-thumb"]:-moz-system-metric(scrollbar-thumb-proportional) {
-  -moz-box-flex: 1;
-}
-
 /******** scrollbox ********/
 
 scrollbox {