diff --git a/content/base/public/nsIFrameLoader.idl b/content/base/public/nsIFrameLoader.idl
index ec54aad9d23..f17c97658de 100644
--- a/content/base/public/nsIFrameLoader.idl
+++ b/content/base/public/nsIFrameLoader.idl
@@ -92,6 +92,18 @@ interface nsIContentView : nsISupports
   readonly attribute float scrollX;
   readonly attribute float scrollY;
 
+  /**
+   * Dimensions of the viewport in chrome-document CSS pixels.
+   */
+  readonly attribute float viewportWidth;
+  readonly attribute float viewportHeight;
+
+  /**
+   * Dimensions of scrolled content in chrome-document CSS pixels.
+   */
+  readonly attribute float contentWidth;
+  readonly attribute float contentHeight;
+
   /**
    * ID that can be used in conjunction with nsIDOMWindowUtils to change
    * the actual document, instead of just how it is transformed.
diff --git a/content/base/src/nsFrameLoader.cpp b/content/base/src/nsFrameLoader.cpp
index 9b9d8fdddd7..6a0ddef9c2a 100644
--- a/content/base/src/nsFrameLoader.cpp
+++ b/content/base/src/nsFrameLoader.cpp
@@ -236,6 +236,34 @@ nsContentView::GetScrollY(float* aViewScrollY)
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsContentView::GetViewportWidth(float* aWidth)
+{
+  *aWidth = nsPresContext::AppUnitsToFloatCSSPixels(mViewportSize.width);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsContentView::GetViewportHeight(float* aHeight)
+{
+  *aHeight = nsPresContext::AppUnitsToFloatCSSPixels(mViewportSize.height);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsContentView::GetContentWidth(float* aWidth)
+{
+  *aWidth = nsPresContext::AppUnitsToFloatCSSPixels(mContentSize.width);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsContentView::GetContentHeight(float* aHeight)
+{
+  *aHeight = nsPresContext::AppUnitsToFloatCSSPixels(mContentSize.height);
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsContentView::GetId(nsContentViewId* aId)
 {
diff --git a/content/base/src/nsFrameLoader.h b/content/base/src/nsFrameLoader.h
index 7aceff60310..c34655a9e52 100644
--- a/content/base/src/nsFrameLoader.h
+++ b/content/base/src/nsFrameLoader.h
@@ -131,7 +131,9 @@ public:
 
   nsContentView(nsIContent* aOwnerContent, ViewID aScrollId,
                 ViewConfig aConfig = ViewConfig())
-    : mOwnerContent(aOwnerContent)
+    : mViewportSize(0, 0)
+    , mContentSize(0, 0)
+    , mOwnerContent(aOwnerContent)
     , mScrollId(aScrollId)
     , mConfig(aConfig)
   {}
@@ -148,6 +150,9 @@ public:
     return mConfig;
   }
 
+  nsSize mViewportSize;
+  nsSize mContentSize;
+
   nsIContent *mOwnerContent; // WEAK
 
 private:
diff --git a/gfx/layers/Layers.h b/gfx/layers/Layers.h
index d85ddf7c40c..1bd8786dc46 100644
--- a/gfx/layers/Layers.h
+++ b/gfx/layers/Layers.h
@@ -97,6 +97,7 @@ public:
 
   FrameMetrics()
     : mViewport(0, 0, 0, 0)
+    , mContentSize(0, 0)
     , mViewportScrollOffset(0, 0)
     , mScrollId(NULL_SCROLL_ID)
   {}
@@ -127,6 +128,7 @@ public:
   }
 
   nsIntRect mViewport;
+  nsIntSize mContentSize;
   nsIntPoint mViewportScrollOffset;
   nsIntRect mDisplayPort;
   ViewID mScrollId;
diff --git a/gfx/layers/ipc/ShadowLayerUtils.h b/gfx/layers/ipc/ShadowLayerUtils.h
index 4fff40cfe2b..baf2eb8f4c2 100644
--- a/gfx/layers/ipc/ShadowLayerUtils.h
+++ b/gfx/layers/ipc/ShadowLayerUtils.h
@@ -64,6 +64,7 @@ struct ParamTraits<mozilla::layers::FrameMetrics>
   static void Write(Message* aMsg, const paramType& aParam)
   {
     WriteParam(aMsg, aParam.mViewport);
+    WriteParam(aMsg, aParam.mContentSize);
     WriteParam(aMsg, aParam.mViewportScrollOffset);
     WriteParam(aMsg, aParam.mDisplayPort);
     WriteParam(aMsg, aParam.mScrollId);
@@ -72,6 +73,7 @@ struct ParamTraits<mozilla::layers::FrameMetrics>
   static bool Read(const Message* aMsg, void** aIter, paramType* aResult)
   {
     return (ReadParam(aMsg, aIter, &aResult->mViewport) &&
+            ReadParam(aMsg, aIter, &aResult->mContentSize) &&
             ReadParam(aMsg, aIter, &aResult->mViewportScrollOffset) &&
             ReadParam(aMsg, aIter, &aResult->mDisplayPort) &&
             ReadParam(aMsg, aIter, &aResult->mScrollId));
diff --git a/layout/base/nsDisplayList.cpp b/layout/base/nsDisplayList.cpp
index 861bbde571b..cfcb3647a20 100644
--- a/layout/base/nsDisplayList.cpp
+++ b/layout/base/nsDisplayList.cpp
@@ -173,6 +173,12 @@ static void RecordFrameMetrics(nsIFrame* aForFrame,
   nsIScrollableFrame* rootScrollableFrame =
     presShell->GetRootScrollFrameAsScrollable();
   if (rootScrollableFrame) {
+    nsSize contentSize = 
+      rootScrollableFrame->GetScrollRange().Size() +
+      rootScrollableFrame->GetScrollPortRect().Size();
+    metrics.mContentSize = nsIntSize(NSAppUnitsToIntPixels(contentSize.width, auPerDevPixel),
+                                     NSAppUnitsToIntPixels(contentSize.height, auPerDevPixel));
+
     metrics.mViewportScrollOffset =
       rootScrollableFrame->GetScrollPosition().ToNearestPixels(auPerDevPixel);
     
diff --git a/layout/ipc/RenderFrameParent.cpp b/layout/ipc/RenderFrameParent.cpp
index b071051ebd9..da61fcff4a7 100644
--- a/layout/ipc/RenderFrameParent.cpp
+++ b/layout/ipc/RenderFrameParent.cpp
@@ -372,6 +372,13 @@ BuildViewMap(ViewMap& oldContentViews, ViewMap& newContentViews,
     view = new nsContentView(aFrameLoader->GetOwnerContent(), scrollId, config);
   }
 
+  view->mViewportSize = nsSize(
+    NSIntPixelsToAppUnits(metrics.mViewport.width, auPerDevPixel) * aXScale,
+    NSIntPixelsToAppUnits(metrics.mViewport.height, auPerDevPixel) * aYScale);
+  view->mContentSize = nsSize(
+    NSIntPixelsToAppUnits(metrics.mContentSize.width, auPerDevPixel) * aXScale,
+    NSIntPixelsToAppUnits(metrics.mContentSize.height, auPerDevPixel) * aYScale);
+
   newContentViews.insert(ViewMap::value_type(scrollId, view));
 
   for (Layer* child = aLayer->GetFirstChild();