Implement a benchmark for GrResourceCache

include/core/SkCanvas.h

Index: include/core/SkCanvas.h
diff --git a/include/core/SkCanvas.h b/include/core/SkCanvas.h
index d831a5c11fe5bede41ceb3b4bc9ee0ab6b7d339c..7bcc09a7290aa6327fc50a0edc5ba3d7f7cd1dd8 100644
--- a/include/core/SkCanvas.h
+++ b/include/core/SkCanvas.h
@@ -29,6 +29,7 @@ class SkMetaData;
 class SkPicture;
 class SkRRect;
 class SkSurface_Base;
+class GrContext;
 
 /** \class SkCanvas
 
@@ -109,6 +110,12 @@ public:
                                          int width, int height,
                                          bool isOpaque);
 
+    /**
+     * Return the GPU context of the device that is associated with the canvas.
+     * For a canvas with non-GPU device, NULL is returned.
+     */
+    GrContext* getGrContext();
+
     ///////////////////////////////////////////////////////////////////////////
 
     /**