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 203f39d68eca5aba6e3818d7770d317d3a25b230..46bc5a2c9d24c1a19ebe0d3d572ab4e4f1a8e040 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"
@@ -893,6 +894,9 @@ void FrameView::performLayout(RenderObject* rootForThisLayout, bool inSubtreeLay
         LayoutIndicator layoutIndicator;
         rootForThisLayout->layout();
         gatherDebugLayoutRects(rootForThisLayout);
+
+        ResourceLoadPriorityOptimizer modifier;
+        rootForThisLayout->didLayout(modifier);
     }
 
     TextAutosizer* textAutosizer = frame().document()->textAutosizer();
@@ -902,6 +906,9 @@ void FrameView::performLayout(RenderObject* rootForThisLayout, bool inSubtreeLay
         LayoutIndicator layoutIndicator;
         rootForThisLayout->layout();
         gatherDebugLayoutRects(rootForThisLayout);
+
+        ResourceLoadPriorityOptimizer modifier;
+        rootForThisLayout->didLayout(modifier);
     }
 
     m_inLayout = false;
@@ -1670,6 +1677,11 @@ void FrameView::scrollPositionChanged()
         if (renderView->usesCompositing())
             renderView->compositor()->frameViewDidScroll();
     }
+
+    if (m_frame->document() && m_frame->document()->renderer()) {
+        ResourceLoadPriorityOptimizer modifier;
+        m_frame->document()->renderer()->didScroll(modifier);
+    }
 }
 
 void FrameView::repaintFixedElementsAfterScrolling()