Add hooks for GL_EXT_debug_marker in gpu

src/gpu/GrGpu.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGpu_DEFINED
 #define GrGpu_DEFINED
 
@@ skipping 440 matching lines @@
 
     // overridden by backend-specific derived class to perform the texture update
     virtual bool onWriteTexturePixels(GrTexture* texture,
                                       int left, int top, int width, int height,
                                       GrPixelConfig config, const void* buffer,
                                       size_t rowBytes) = 0;
 
     // overridden by backend-specific derived class to perform the resolve
     virtual void onResolveRenderTarget(GrRenderTarget* target) = 0;
 
+    // GrDrawTarget Overrides
+    virtual void onInsertEventMarker(const char* marker) SK_OVERRIDE = 0;
+    virtual void onPushGroupMarker(const char* marker) SK_OVERRIDE = 0;
+    virtual void onPopGroupMarker() SK_OVERRIDE = 0;
+
     // width and height may be larger than rt (if underlying API allows it).
     // Should attach the SB to the RT. Returns false if compatible sb could
     // not be created.
     virtual bool createStencilBufferForRenderTarget(GrRenderTarget*, int width, int height) = 0;
 
     // attaches an existing SB to an existing RT.
     virtual bool attachStencilBufferToRenderTarget(GrStencilBuffer*, GrRenderTarget*) = 0;
 
     // The GrGpu typically records the clients requested state and then flushes
     // deltas from previous state at draw time. This function does the
@@ skipping 48 matching lines @@
     // these are mutable so they can be created on-demand
     mutable GrIndexBuffer*                                              fQuadIndexBuffer;
     // Used to abandon/release all resources created by this GrGpu. TODO: Move this
     // functionality to GrResourceCache.
     ResourceList                                                        fResourceList;
 
     typedef GrDrawTarget INHERITED;
 };
 
 #endif