Adds DevTools commands for forced viewport override.

third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp

Index: third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp b/third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp
index 494b08fe2afcb9ae65eae7f2615d19ae5ccda712..ff3220e1ad615c59a4900e8f1800b35c17d53406 100644
--- a/third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp
+++ b/third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp
@@ -121,7 +121,6 @@ GraphicsLayer::GraphicsLayer(GraphicsLayerClient* client)
     , m_contentsOpaque(false)
     , m_shouldFlattenTransform(true)
     , m_backfaceVisibility(true)
-    , m_masksToBounds(false)
     , m_drawsContent(false)
     , m_contentsVisible(true)
     , m_isRootForIsolatedGroup(false)
@@ -958,10 +957,14 @@ void GraphicsLayer::setRenderingContext(int context)
         m_contentsLayer->setRenderingContext(m_3dRenderingContext);
 }
 
+bool GraphicsLayer::masksToBounds() const
+{
+    return m_layer->layer()->masksToBounds();
+}
+
 void GraphicsLayer::setMasksToBounds(bool masksToBounds)
 {
-    m_masksToBounds = masksToBounds;
-    m_layer->layer()->setMasksToBounds(m_masksToBounds);
+    m_layer->layer()->setMasksToBounds(masksToBounds);
 }
 
 void GraphicsLayer::setDrawsContent(bool drawsContent)