Raise the loading priority of in-viewport images.

Source/core/frame/FrameView.cpp

Index: Source/core/frame/FrameView.cpp
diff --git a/Source/core/frame/FrameView.cpp b/Source/core/frame/FrameView.cpp
index aa4988f149f2db66f85fdc75c814b79b31926950..1fe8afd98beab13368f4685b39d707a544abe089 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -36,6 +36,7 @@
 #include "core/editing/FrameSelection.h"
 #include "core/events/OverflowEvent.h"
 #include "core/fetch/ResourceFetcher.h"
+#include "core/fetch/ResourceLoadPriorityOptimizer.h"
 #include "core/fetch/TextResourceDecoder.h"
 #include "core/html/HTMLFrameElement.h"
 #include "core/html/HTMLHtmlElement.h"
@@ -907,6 +908,9 @@ void FrameView::performLayout(RenderObject* rootForThisLayout, bool inSubtreeLay
 
         LayoutIndicator layoutIndicator;
         rootForThisLayout->layout();
+
+        ResourceLoadPriorityOptimizer modifier;
+        rootForThisLayout->didLayout(modifier);
     }
 
     bool autosized = frame().document()->textAutosizer()->processSubtree(rootForThisLayout);
@@ -914,6 +918,9 @@ void FrameView::performLayout(RenderObject* rootForThisLayout, bool inSubtreeLay
         TRACE_EVENT0("webkit", "2nd layout due to Text Autosizing");
         LayoutIndicator layoutIndicator;
         rootForThisLayout->layout();
+
+        ResourceLoadPriorityOptimizer modifier;
+        rootForThisLayout->didLayout(modifier);
     }
 
     m_inLayout = false;
@@ -1662,6 +1669,9 @@ void FrameView::scrollPositionChanged()
         if (renderView->usesCompositing())
             renderView->compositor()->frameViewDidScroll();
     }
+
+    ResourceLoadPriorityOptimizer modifier;
+    m_frame->document()->renderer()->didScroll(modifier);
 }
 
 void FrameView::repaintFixedElementsAfterScrolling()