Bug 1023557 - Store the content description in ContainerLayer instead of FrameMetrics. r=kats,BenWa

gfx/ipc/GfxMessageUtils.h

@@ -740,46 +740,33 @@ struct ParamTraits<mozilla::layers::FrameMetrics>
     WriteParam(aMsg, aParam.mHasScrollgrab);
     WriteParam(aMsg, aParam.mUpdateScrollOffset);
     WriteParam(aMsg, aParam.mScrollGeneration);
-    aMsg->WriteBytes(aParam.mContentDescription,
-                     sizeof(aParam.mContentDescription));
     WriteParam(aMsg, aParam.mTransformScale);
   }
 
   static bool Read(const Message* aMsg, void** aIter, paramType* aResult)
   {
-    const char* contentDescription;
+    return (ReadParam(aMsg, aIter, &aResult->mScrollableRect) &&
-    if (!(ReadParam(aMsg, aIter, &aResult->mScrollableRect) &&
+            ReadParam(aMsg, aIter, &aResult->mViewport) &&
-          ReadParam(aMsg, aIter, &aResult->mViewport) &&
+            ReadParam(aMsg, aIter, &aResult->mScrollOffset) &&
-          ReadParam(aMsg, aIter, &aResult->mScrollOffset) &&
+            ReadParam(aMsg, aIter, &aResult->mDisplayPort) &&
-          ReadParam(aMsg, aIter, &aResult->mDisplayPort) &&
+            ReadParam(aMsg, aIter, &aResult->mDisplayPortMargins) &&
-          ReadParam(aMsg, aIter, &aResult->mDisplayPortMargins) &&
+            ReadParam(aMsg, aIter, &aResult->mUseDisplayPortMargins) &&
-          ReadParam(aMsg, aIter, &aResult->mUseDisplayPortMargins) &&
+            ReadParam(aMsg, aIter, &aResult->mCriticalDisplayPort) &&
-          ReadParam(aMsg, aIter, &aResult->mCriticalDisplayPort) &&
+            ReadParam(aMsg, aIter, &aResult->mCompositionBounds) &&
-          ReadParam(aMsg, aIter, &aResult->mCompositionBounds) &&
+            ReadParam(aMsg, aIter, &aResult->mRootCompositionSize) &&
-          ReadParam(aMsg, aIter, &aResult->mRootCompositionSize) &&
+            ReadParam(aMsg, aIter, &aResult->mScrollId) &&
-          ReadParam(aMsg, aIter, &aResult->mScrollId) &&
+            ReadParam(aMsg, aIter, &aResult->mResolution) &&
-          ReadParam(aMsg, aIter, &aResult->mResolution) &&
+            ReadParam(aMsg, aIter, &aResult->mCumulativeResolution) &&
-          ReadParam(aMsg, aIter, &aResult->mCumulativeResolution) &&
+            ReadParam(aMsg, aIter, &aResult->mZoom) &&
-          ReadParam(aMsg, aIter, &aResult->mZoom) &&
+            ReadParam(aMsg, aIter, &aResult->mDevPixelsPerCSSPixel) &&
-          ReadParam(aMsg, aIter, &aResult->mDevPixelsPerCSSPixel) &&
+            ReadParam(aMsg, aIter, &aResult->mMayHaveTouchListeners) &&
-          ReadParam(aMsg, aIter, &aResult->mMayHaveTouchListeners) &&
+            ReadParam(aMsg, aIter, &aResult->mMayHaveTouchCaret) &&
-          ReadParam(aMsg, aIter, &aResult->mMayHaveTouchCaret) &&
+            ReadParam(aMsg, aIter, &aResult->mPresShellId) &&
-          ReadParam(aMsg, aIter, &aResult->mPresShellId) &&
+            ReadParam(aMsg, aIter, &aResult->mIsRoot) &&
-          ReadParam(aMsg, aIter, &aResult->mIsRoot) &&
+            ReadParam(aMsg, aIter, &aResult->mHasScrollgrab) &&
-          ReadParam(aMsg, aIter, &aResult->mHasScrollgrab) &&
+            ReadParam(aMsg, aIter, &aResult->mUpdateScrollOffset) &&
-          ReadParam(aMsg, aIter, &aResult->mUpdateScrollOffset) &&
+            ReadParam(aMsg, aIter, &aResult->mScrollGeneration) &&
-          ReadParam(aMsg, aIter, &aResult->mScrollGeneration) &&
+            ReadParam(aMsg, aIter, &aResult->mTransformScale));
-          aMsg->ReadBytes(aIter, &contentDescription,
-                          sizeof(aResult->mContentDescription)) &&
-          ReadParam(aMsg, aIter, &aResult->mTransformScale))) {
-      return false;
-    }
-    // ReadBytes() doesn't actually copy the string, it only points
-    // a pointer to the string in its internal buffer.
-    strncpy(aResult->mContentDescription, contentDescription,
-            sizeof(aResult->mContentDescription));
-    aResult->mContentDescription[sizeof(aResult->mContentDescription) - 1] = '\0';
-    return true;
   }
 };
 

gfx/layers/FrameMetrics.h

@@ -7,7 +7,6 @@
 #define GFX_FRAMEMETRICS_H
 
 #include <stdint.h>                     // for uint32_t, uint64_t
-#include <string>                       // for std::string
 #include "Units.h"                      // for CSSRect, CSSPixel, etc
 #include "mozilla/gfx/BasePoint.h"      // for BasePoint
 #include "mozilla/gfx/Rect.h"           // for RoundedIn
@@ -92,7 +91,6 @@ public:
     , mZoom(1)
     , mUpdateScrollOffset(false)
     , mScrollGeneration(0)
-    , mContentDescription()
     , mRootCompositionSize(0, 0)
     , mDisplayPortMargins(0, 0, 0, 0)
     , mUseDisplayPortMargins(false)
@@ -103,8 +101,6 @@ public:
 
   bool operator==(const FrameMetrics& aOther) const
   {
-    // mContentDescription is not compared on purpose as it's only used
-    // for debugging.
     return mCompositionBounds.IsEqualEdges(aOther.mCompositionBounds) &&
            mRootCompositionSize == aOther.mRootCompositionSize &&
            mDisplayPort.IsEqualEdges(aOther.mDisplayPort) &&
@@ -402,18 +398,6 @@ public:
     return mScrollGeneration;
   }
 
-  std::string GetContentDescription() const
-  {
-    return std::string(mContentDescription);
-  }
-
-  void SetContentDescription(const std::string& aContentDescription)
-  {
-    strncpy(mContentDescription, aContentDescription.c_str(), sizeof(mContentDescription));
-    // forcibly null-terminate in case aContentDescription is too long
-    mContentDescription[sizeof(mContentDescription) - 1] = '\0';
-  }
-
   ViewID GetScrollId() const
   {
     return mScrollId;
@@ -503,10 +487,6 @@ private:
   // The scroll generation counter used to acknowledge the scroll offset update.
   uint32_t mScrollGeneration;
 
-  // A description of the content element corresponding to this frame.
-  // This is empty unless the apz.printtree pref is turned on.
-  char mContentDescription[20];
-
   // The size of the root scrollable's composition bounds, but in local CSS pixels.
   CSSSize mRootCompositionSize;
 

gfx/layers/Layers.cpp

@@ -922,7 +922,7 @@ ContainerLayer::FillSpecificAttributes(SpecificLayerAttributes& aAttrs)
   aAttrs = ContainerLayerAttributes(GetFrameMetrics(), mScrollHandoffParentId,
                                     mPreXScale, mPreYScale,
                                     mInheritedXScale, mInheritedYScale,
-                                    mBackgroundColor);
+                                    mBackgroundColor, mContentDescription);
 }
 
 bool

gfx/layers/Layers.h

@@ -1770,6 +1770,17 @@ public:
     Mutated();
   }
 
+  void SetContentDescription(const std::string& aContentDescription)
+  {
+    if (mContentDescription == aContentDescription) {
+      return;
+    }
+
+    MOZ_LAYERS_LOG_IF_SHADOWABLE(this, ("Layer::Mutated(%p) ContentDescription", this));
+    mContentDescription = aContentDescription;
+    Mutated();
+  }
+
   virtual void FillSpecificAttributes(SpecificLayerAttributes& aAttrs);
 
   void SortChildrenBy3DZOrder(nsTArray<Layer*>& aArray);
@@ -1789,6 +1800,7 @@ public:
   float GetInheritedYScale() const { return mInheritedYScale; }
 
   gfxRGBA GetBackgroundColor() const { return mBackgroundColor; }
+  const std::string& GetContentDescription() const { return mContentDescription; }
 
   MOZ_LAYER_DECL_NAME("ContainerLayer", TYPE_CONTAINER)
 
@@ -1881,6 +1893,10 @@ protected:
   // When multi-layer-apz (bug 967844) is implemented, this is likely to move
   // elsewhere (e.g. to Layer).
   gfxRGBA mBackgroundColor;
+  // A description of the content element corresponding to this frame.
+  // This is empty unless this ContainerLayer is scrollable and the
+  // apz.printtree pref is turned on.
+  std::string mContentDescription;
   bool mUseIntermediateSurface;
   bool mSupportsComponentAlphaChildren;
   bool mMayHaveReadbackChild;

gfx/layers/apz/src/APZCTreeManager.cpp

@@ -269,7 +269,7 @@ APZCTreeManager::UpdatePanZoomControllerTree(CompositorParent* aCompositor,
                      << "\tsr=" << container->GetFrameMetrics().mScrollableRect
                      << (aLayer->GetVisibleRegion().IsEmpty() ? "\tscrollinfo" : "")
                      << (apzc->HasScrollgrab() ? "\tscrollgrab" : "")
-                     << "\t" << container->GetFrameMetrics().GetContentDescription();
+                     << "\t" << container->GetContentDescription();
 
         // Bind the APZC instance into the tree of APZCs
         if (aNextSibling) {

gfx/layers/ipc/LayerTransactionParent.cpp

@@ -353,6 +353,7 @@ LayerTransactionParent::RecvUpdate(const InfallibleTArray<Edit>& cset,
         containerLayer->SetPreScale(attrs.preXScale(), attrs.preYScale());
         containerLayer->SetInheritedScale(attrs.inheritedXScale(), attrs.inheritedYScale());
         containerLayer->SetBackgroundColor(attrs.backgroundColor().value());
+        containerLayer->SetContentDescription(attrs.contentDescription());
         break;
       }
       case Specific::TColorLayerAttributes: {

gfx/layers/ipc/LayersMessages.ipdlh

@@ -41,6 +41,7 @@ using mozilla::layers::FrameMetrics::ViewID from "FrameMetrics.h";
 using struct mozilla::layers::FenceHandle from "mozilla/layers/FenceUtils.h";
 using struct mozilla::layers::FenceHandleFromChild from "mozilla/layers/FenceUtils.h";
 using mozilla::layers::TextureIdentifier from "mozilla/layers/CompositorTypes.h";
+using std::string from "string";
 
 namespace mozilla {
 namespace layers {
@@ -227,6 +228,7 @@ struct ContainerLayerAttributes {
   float inheritedXScale;
   float inheritedYScale;
   LayerColor backgroundColor;
+  string contentDescription;
 };
 struct ColorLayerAttributes     { LayerColor color; nsIntRect bounds; };
 struct CanvasLayerAttributes    { GraphicsFilterType filter; nsIntRect bounds; };

layout/base/nsDisplayList.cpp

@@ -814,7 +814,7 @@ static void RecordFrameMetrics(nsIFrame* aForFrame,
     if (nsIContent* content = frameForCompositionBoundsCalculation->GetContent()) {
       nsAutoString contentDescription;
       content->Describe(contentDescription);
-      metrics.SetContentDescription(NS_LossyConvertUTF16toASCII(contentDescription).get());
+      aRoot->SetContentDescription(NS_LossyConvertUTF16toASCII(contentDescription).get());
     }
   }