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 89557d2e07e9ce88aabf89a44996771d273f8849..a457a2caa3566dfe78a288d13f015d83a99599f8 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -37,6 +37,7 @@
 #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"
@@ -910,6 +911,9 @@ void FrameView::performLayout(RenderObject* rootForThisLayout, bool inSubtreeLay
         LayoutIndicator layoutIndicator;
         rootForThisLayout->layout();
         gatherDebugLayoutRects(rootForThisLayout);
+
+        ResourceLoadPriorityOptimizer modifier;
+        rootForThisLayout->didLayout(modifier);
     }
 
     TextAutosizer* textAutosizer = frame().document()->textAutosizer();
@@ -919,6 +923,9 @@ void FrameView::performLayout(RenderObject* rootForThisLayout, bool inSubtreeLay
         LayoutIndicator layoutIndicator;
         rootForThisLayout->layout();
         gatherDebugLayoutRects(rootForThisLayout);
+
+        ResourceLoadPriorityOptimizer modifier;
+        rootForThisLayout->didLayout(modifier);
     }
 
     m_inLayout = false;
@@ -1686,6 +1693,9 @@ void FrameView::scrollPositionChanged()
         if (renderView->usesCompositing())
             renderView->compositor()->frameViewDidScroll();
     }
+
+    ResourceLoadPriorityOptimizer modifier;
+    m_frame->document()->renderer()->didScroll(modifier);
 }
 
 void FrameView::repaintFixedElementsAfterScrolling()