Add test plumbing so that layout tests can query whether a compositor frame was requested

content/shell/renderer/test_runner/WebTestProxy.h

Index: content/shell/renderer/test_runner/WebTestProxy.h
diff --git a/content/shell/renderer/test_runner/WebTestProxy.h b/content/shell/renderer/test_runner/WebTestProxy.h
index a5680c5c1c8c4e8f3c454d0b093d60985cc4c502..111cb1013de0193dcc8671154c81b424b8aa76fa 100644
--- a/content/shell/renderer/test_runner/WebTestProxy.h
+++ b/content/shell/renderer/test_runner/WebTestProxy.h
@@ -134,6 +134,7 @@ protected:
     void didInvalidateRect(const blink::WebRect&);
     void didScrollRect(int, int, const blink::WebRect&);
     void scheduleAnimation();
+    bool isCompositorFramePending() const;
     // FIXME: Remove once we switch to use didForceResize.
     void setWindowRect(const blink::WebRect&);
     void show(blink::WebNavigationPolicy);
@@ -258,6 +259,10 @@ public:
     {
         WebTestProxyBase::scheduleAnimation();
     }
+    virtual bool isCompositorFramePending() const
+    {
+        return WebTestProxyBase::isCompositorFramePending();
+    }
     virtual void setWindowRect(const blink::WebRect& rect)
     {
         WebTestProxyBase::setWindowRect(rect);