Revert 171569 as it broke some browser_tests on win_aura.

content/common/gpu/client/gl_helper.h

Index: content/common/gpu/client/gl_helper.h
===================================================================
--- content/common/gpu/client/gl_helper.h	(revision 171661)
+++ content/common/gpu/client/gl_helper.h	(working copy)
@@ -16,8 +16,6 @@
 class Size;
 }
 
-class SkRegion;
-
 namespace content {
 
 // Provides higher level operations on top of the WebKit::WebGraphicsContext3D
@@ -68,12 +66,6 @@
   WebKit::WebGLId CompileShaderFromSource(const WebKit::WGC3Dchar* source,
                                           WebKit::WGC3Denum type);
 
-  // Copies all pixels from |previous_texture| into |texture| that are
-  // inside the region covered by |old_damage| but not part of |new_damage|.
-  void CopySubBufferDamage(WebKit::WebGLId texture,
-                           WebKit::WebGLId previous_texture,
-                           const SkRegion& new_damage,
-                           const SkRegion& old_damage);
  private:
   class CopyTextureToImpl;