Re-backout c216ff19d690 (bug 1059014 part 3) because the removed code is less dead than it first appears.

--HG--
extra : rebase_source : 22c84e309f8b9e26c359108905a2e8a6e5df2bb7

docshell/base/nsIContentViewer.idl

@@ -31,7 +31,7 @@ class nsDOMNavigationTiming;
 [ptr] native nsDOMNavigationTimingPtr(nsDOMNavigationTiming);
 [ref] native nsIContentViewerTArray(nsTArray<nsCOMPtr<nsIContentViewer> >);
 
-[scriptable, builtinclass, uuid(91b6c1f3-fc5f-43a9-88f4-9286bd19387f)]
+[scriptable, builtinclass, uuid(2da17016-7851-4a45-a7a8-00b360e01595)]
 interface nsIContentViewer : nsISupports
 {
   [noscript] void init(in nsIWidgetPtr aParentWidget,
@@ -229,6 +229,18 @@ interface nsIContentViewer : nsISupports
    */
   [noscript] void appendSubtree(in nsIContentViewerTArray array);
 
+  /**
+   * Instruct the refresh driver to discontinue painting until further
+   * notice.
+   */
+  void pausePainting();
+
+  /**
+   * Instruct the refresh driver to resume painting after a previous call to
+   * pausePainting().
+   */
+  void resumePainting();
+
   /*
    * Render the document as if being viewed on a device with the specified
    * media type. This will cause a reflow.

layout/base/nsDocumentViewer.cpp

@@ -2779,6 +2779,17 @@ nsDocumentViewer::CallChildren(CallChildFunc aFunc, void* aClosure)
   }
 }
 
+static void
+ChangeChildPaintingEnabled(nsIContentViewer* aChild, void* aClosure)
+{
+  bool* enablePainting = (bool*) aClosure;
+  if (*enablePainting) {
+    aChild->ResumePainting();
+  } else {
+    aChild->PausePainting();
+  }
+}
+
 struct ZoomInfo
 {
   float mZoom;
@@ -3208,6 +3219,34 @@ NS_IMETHODIMP nsDocumentViewer::AppendSubtree(nsTArray<nsCOMPtr<nsIContentViewer
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsDocumentViewer::PausePainting()
+{
+  bool enablePaint = false;
+  CallChildren(ChangeChildPaintingEnabled, &enablePaint);
+
+  nsIPresShell* presShell = GetPresShell();
+  if (presShell) {
+    presShell->PausePainting();
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocumentViewer::ResumePainting()
+{
+  bool enablePaint = true;
+  CallChildren(ChangeChildPaintingEnabled, &enablePaint);
+
+  nsIPresShell* presShell = GetPresShell();
+  if (presShell) {
+    presShell->ResumePainting();
+  }
+
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsDocumentViewer::GetContentSize(int32_t* aWidth, int32_t* aHeight)
 {

layout/base/nsIPresShell.h

@@ -137,10 +137,10 @@ typedef struct CapturingContentInfo {
   mozilla::StaticRefPtr<nsIContent> mContent;
 } CapturingContentInfo;
 
-// 6654f67f-c5aa-4934-b611-6d8d01e6193f
+// f17842ee-f1f0-4193-814f-70d706b67060
 #define NS_IPRESSHELL_IID \
-{ 0x6654f67f, 0xc5aa, 0x4934, \
-  { 0xb6, 0x11, 0x6d, 0x8d, 0x01, 0xe6, 0x19, 0x3f } }
+{ 0xf17842ee, 0xf1f0, 0x4193, \
+  { 0x81, 0x4f, 0x70, 0xd7, 0x06, 0xb6, 0x70, 0x60 } }
 
 // debug VerifyReflow flags
 #define VERIFY_REFLOW_ON                    0x01
@@ -908,6 +908,20 @@ public:
    */
   bool IsPaintingSuppressed() const { return mPaintingSuppressed; }
 
+  /**
+   * Pause painting by freezing the refresh driver of this and all parent
+   * presentations. This may not have the desired effect if this pres shell
+   * has its own refresh driver.
+   */
+  virtual void PausePainting() = 0;
+
+  /**
+   * Resume painting by thawing the refresh driver of this and all parent
+   * presentations. This may not have the desired effect if this pres shell
+   * has its own refresh driver.
+   */
+  virtual void ResumePainting() = 0;
+
   /**
    * Unsuppress painting.
    */
@@ -1781,6 +1795,7 @@ protected:
   bool mFontSizeInflationForceEnabled;
   bool mFontSizeInflationDisabledInMasterProcess;
   bool mFontSizeInflationEnabled;
+  bool mPaintingIsFrozen;
 
   // Dirty bit indicating that mFontSizeInflationEnabled needs to be recomputed.
   bool mFontSizeInflationEnabledIsDirty;

layout/base/nsPresShell.cpp

@@ -777,6 +777,7 @@ PresShell::PresShell()
     addedPointerEventEnabled = true;
   }
 
+  mPaintingIsFrozen = false;
   mHasCSSBackgroundColor = true;
   mIsLastChromeOnlyEscapeKeyConsumed = false;
   mHasReceivedPaintMessage = false;
@@ -800,6 +801,13 @@ PresShell::~PresShell()
                mLastCallbackEventRequest == nullptr,
                "post-reflow queues not empty.  This means we're leaking");
 
+  // Verify that if painting was frozen, but we're being removed from the tree,
+  // that we now re-enable painting on our refresh driver, since it may need to
+  // be re-used by another presentation.
+  if (mPaintingIsFrozen) {
+    mPresContext->RefreshDriver()->Thaw();
+  }
+
 #ifdef DEBUG
   MOZ_ASSERT(mPresArenaAllocCount == 0,
              "Some pres arena objects were not freed");
@@ -10724,6 +10732,26 @@ nsIPresShell::FontSizeInflationEnabled()
   return mFontSizeInflationEnabled;
 }
 
+void
+PresShell::PausePainting()
+{
+  if (GetPresContext()->RefreshDriver()->PresContext() != GetPresContext())
+    return;
+
+  mPaintingIsFrozen = true;
+  GetPresContext()->RefreshDriver()->Freeze();
+}
+
+void
+PresShell::ResumePainting()
+{
+  if (GetPresContext()->RefreshDriver()->PresContext() != GetPresContext())
+    return;
+
+  mPaintingIsFrozen = false;
+  GetPresContext()->RefreshDriver()->Thaw();
+}
+
 void
 nsIPresShell::SyncWindowProperties(nsView* aView)
 {

layout/base/nsPresShell.h

@@ -722,6 +722,10 @@ protected:
 #ifdef ANDROID
   virtual nsIDocument* GetTouchEventTargetDocument();
 #endif
+
+  virtual void PausePainting() override;
+  virtual void ResumePainting() override;
+
   void UpdateImageVisibility();
   void UpdateActivePointerState(mozilla::WidgetGUIEvent* aEvent);