Bug 1158557 - Don't throttle rAF for documents with live static clones. r=smaug

--HG--
extra : rebase_source : a772e11a221489c1085ad62572e23cfbbf080353

dom/base/nsDocument.cpp

@@ -1636,6 +1636,8 @@ nsIDocument::~nsIDocument()
   if (mNodeInfoManager) {
     mNodeInfoManager->DropDocumentReference();
   }
+
+  UnlinkOriginalDocumentIfStatic();
 }
 
 
@@ -2093,13 +2095,14 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsDocument)
   }
   tmp->mFirstChild = nullptr;
 
+  tmp->UnlinkOriginalDocumentIfStatic();
+
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mXPathEvaluator)
   tmp->mCachedRootElement = nullptr; // Avoid a dangling pointer
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mDisplayDocument)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mFirstBaseNodeWithHref)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mDOMImplementation)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mImageMaps)
-  NS_IMPL_CYCLE_COLLECTION_UNLINK(mOriginalDocument)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mCachedEncoder)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mUndoManager)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mDocumentTimeline)
@@ -3925,6 +3928,11 @@ nsIDocument::TakeFrameRequestCallbacks(FrameRequestCallbackList& aCallbacks)
 bool
 nsIDocument::ShouldThrottleFrameRequests()
 {
+  if (mStaticCloneCount > 0) {
+    // Even if we're not visible, a static clone may be, so run at full speed.
+    return false;
+  }
+
   if (!mIsShowing) {
     // We're not showing (probably in a background tab or the bf cache).
     return true;
@@ -10280,6 +10288,9 @@ nsIDocument::CreateStaticClone(nsIDocShell* aCloneContainer)
       } else {
         clonedDoc->mOriginalDocument = this;
       }
+
+      clonedDoc->mOriginalDocument->mStaticCloneCount++;
+
       int32_t sheetsCount = GetNumberOfStyleSheets();
       for (int32_t i = 0; i < sheetsCount; ++i) {
         nsRefPtr<CSSStyleSheet> sheet = do_QueryObject(GetStyleSheetAt(i));
@@ -10317,6 +10328,17 @@ nsIDocument::CreateStaticClone(nsIDocShell* aCloneContainer)
   return clonedDoc.forget();
 }
 
+void
+nsIDocument::UnlinkOriginalDocumentIfStatic()
+{
+  if (IsStaticDocument() && mOriginalDocument) {
+    MOZ_ASSERT(mOriginalDocument->mStaticCloneCount > 0);
+    mOriginalDocument->mStaticCloneCount--;
+    mOriginalDocument = nullptr;
+  }
+  MOZ_ASSERT(!mOriginalDocument);
+}
+
 nsresult
 nsIDocument::ScheduleFrameRequestCallback(const FrameRequestCallbackHolder& aCallback,
                                           int32_t *aHandle)

dom/base/nsIDocument.h

@@ -1937,6 +1937,12 @@ public:
     return mOriginalDocument;
   }
 
+  /**
+   * If this document is a static clone, let the original document know that
+   * we're going away and then release our reference to it.
+   */
+  void UnlinkOriginalDocumentIfStatic();
+
   /**
    * These are called by the parser as it encounters <picture> tags, the end of
    * said tags, and possible picture <source srcset> sources respectively. These
@@ -2861,6 +2867,9 @@ protected:
    */
   int32_t mFrameRequestCallbackCounter;
 
+  // Count of live static clones of this document.
+  uint32_t mStaticCloneCount;
+
   // Array of nodes that have been blocked to prevent user tracking.
   // They most likely have had their nsIChannel canceled by the URL
   // classifier. (Safebrowsing)