Add hooks for GL_EXT_debug_marker in gpu

src/gpu/gl/GrGpuGL.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 GrGpuGL_DEFINED
 #define GrGpuGL_DEFINED
 
@@ skipping 134 matching lines @@
                               void* buffer,
                               size_t rowBytes) SK_OVERRIDE;
 
     virtual bool onWriteTexturePixels(GrTexture* texture,
                                       int left, int top, int width, int height,
                                       GrPixelConfig config, const void* buffer,
                                       size_t rowBytes) SK_OVERRIDE;
 
     virtual void onResolveRenderTarget(GrRenderTarget* target) SK_OVERRIDE;
 
+    virtual void onInsertEventMarker(const char* marker) SK_OVERRIDE;
+    virtual void onPushGroupMarker(const char* marker) SK_OVERRIDE;
+    virtual void onPopGroupMarker() SK_OVERRIDE;
+
     virtual void onGpuDraw(const DrawInfo&) SK_OVERRIDE;
 
     virtual void onGpuStencilPath(const GrPath*, SkPath::FillType) SK_OVERRIDE;
     virtual void onGpuDrawPath(const GrPath*, SkPath::FillType) SK_OVERRIDE;
 
     virtual void clearStencil() SK_OVERRIDE;
     virtual void clearStencilClip(const SkIRect& rect,
                                   bool insideClip) SK_OVERRIDE;
     virtual bool flushGraphicsState(DrawType, const GrDeviceCoordTexture* dstCopy) SK_OVERRIDE;
 
@@ skipping 284 matching lines @@
     ///@}
 
     // we record what stencil format worked last time to hopefully exit early
     // from our loop that tries stencil formats and calls check fb status.
     int fLastSuccessfulStencilFmtIdx;
 
     typedef GrGpu INHERITED;
 };
 
 #endif