Bug 812517. Part 2: Call ScrollToCSSPixelsApproximate when TabChild scrolls. r=mats

--HG--
extra : rebase_source : e4c9db69125d21a84400a062630a0c62c3f450d8

dom/base/nsGlobalWindow.h

@@ -511,6 +511,10 @@ public:
     return mIsChrome;
   }
 
+  // GetScrollFrame does not flush.  Callers should do it themselves as needed,
+  // depending on which info they actually want off the scrollable frame.
+  nsIScrollableFrame *GetScrollFrame();
+
   nsresult Observe(nsISupports* aSubject, const char* aTopic,
                    const PRUnichar* aData);
 
@@ -793,9 +797,6 @@ protected:
   nsresult GetTreeOwner(nsIDocShellTreeOwner** aTreeOwner);
   nsresult GetTreeOwner(nsIBaseWindow** aTreeOwner);
   nsresult GetWebBrowserChrome(nsIWebBrowserChrome** aBrowserChrome);
-  // GetScrollFrame does not flush.  Callers should do it themselves as needed,
-  // depending on which info they actually want off the scrollable frame.
-  nsIScrollableFrame *GetScrollFrame();
   nsresult SecurityCheckURL(const char *aURL);
   nsresult BuildURIfromBase(const char *aURL,
                             nsIURI **aBuiltURI,

dom/ipc/TabChild.cpp

@@ -64,6 +64,7 @@
 #include "nsInterfaceHashtable.h"
 #include "nsPIDOMWindow.h"
 #include "nsPIWindowRoot.h"
+#include "nsGlobalWindow.h"
 #include "nsPresContext.h"
 #include "nsPrintfCString.h"
 #include "nsScriptLoader.h"
@@ -1154,6 +1155,17 @@ TabChild::DispatchMessageManagerMessage(const nsAString& aMessageName,
                        aMessageName, false, &cloneData, nullptr, nullptr);
 }
 
+static void
+ScrollWindowTo(nsIDOMWindow* aWindow, const mozilla::gfx::Point& aPoint)
+{
+    nsGlobalWindow* window = static_cast<nsGlobalWindow*>(aWindow);
+    nsIScrollableFrame* sf = window->GetScrollFrame();
+
+    if (sf) {
+        sf->ScrollToCSSPixelsApproximate(aPoint);
+    }
+}
+
 bool
 TabChild::RecvUpdateFrame(const FrameMetrics& aFrameMetrics)
 {
@@ -1199,8 +1211,7 @@ TabChild::RecvUpdateFrame(const FrameMetrics& aFrameMetrics)
       AsyncPanZoomController::CalculateCompositedRectInCssPixels(aFrameMetrics);
     utils->SetScrollPositionClampingScrollPortSize(
       cssCompositedRect.width, cssCompositedRect.height);
-    window->ScrollTo(aFrameMetrics.mScrollOffset.x,
-                     aFrameMetrics.mScrollOffset.y);
+    ScrollWindowTo(window, aFrameMetrics.mScrollOffset);
     gfxSize resolution = AsyncPanZoomController::CalculateResolution(
       aFrameMetrics);
     utils->SetResolution(resolution.width, resolution.height);