aura: use TestWebGraphicsContext3D for the shared contexts

content/common/webkitplatformsupport_impl.h

Index: content/common/webkitplatformsupport_impl.h
diff --git a/content/common/webkitplatformsupport_impl.h b/content/common/webkitplatformsupport_impl.h
index 1ceb213065a81d1b60226747536bc78cec7b34a2..f579ce0d55fd29d9340a761992e411612937659a 100644
--- a/content/common/webkitplatformsupport_impl.h
+++ b/content/common/webkitplatformsupport_impl.h
@@ -19,6 +19,8 @@ namespace content {
 class CONTENT_EXPORT WebKitPlatformSupportImpl
     : NON_EXPORTED_BASE(public webkit_glue::WebKitPlatformSupportImpl) {
  public:
+  typedef WebKit::WebGraphicsContext3D* (OffscreenContextFactory)();
+
   WebKitPlatformSupportImpl();
   virtual ~WebKitPlatformSupportImpl();
 
@@ -37,6 +39,9 @@ class CONTENT_EXPORT WebKitPlatformSupportImpl
   virtual WebKit::WebGraphicsContext3D* createOffscreenGraphicsContext3D(
       const WebKit::WebGraphicsContext3D::Attributes& attributes);
 
+  static void SetOffscreenContextFactoryForTest(
+      OffscreenContextFactory factory);
+
  protected:
   virtual GpuChannelHostFactory* GetGpuChannelHostFactory();
 };
@@ -44,4 +49,3 @@ class CONTENT_EXPORT WebKitPlatformSupportImpl
 }  // namespace content
 
 #endif  // CONTENT_COMMON_CONTENT_WEBKITPLATFORMSUPPORT_IMPL_H_
-