gpu: Add CHROMIUM_gpu_memory_buffer_image extension.

gpu/command_buffer/client/gles2_implementation.h

Index: gpu/command_buffer/client/gles2_implementation.h
diff --git a/gpu/command_buffer/client/gles2_implementation.h b/gpu/command_buffer/client/gles2_implementation.h
index 55cd0a14b748d0e758d37bea20744472ab36e94f..f9e84b19865420fbc3166ea762b7c6ceec1fcff5 100644
--- a/gpu/command_buffer/client/gles2_implementation.h
+++ b/gpu/command_buffer/client/gles2_implementation.h
@@ -555,6 +555,10 @@ class GLES2_IMPL_EXPORT GLES2Implementation
   void UnmapImageCHROMIUMHelper(GLuint image_id);
   void GetImageParameterivCHROMIUMHelper(
       GLuint image_id, GLenum pname, GLint* params);
+  GLuint CreateGpuMemoryBufferImageCHROMIUMHelper(GLsizei width,
+                                                  GLsizei height,
+                                                  GLenum internalformat,
+                                                  GLenum usage);
 
   // Helper for GetVertexAttrib
   bool GetVertexAttribHelper(GLuint index, GLenum pname, uint32* param);