Implement EXT_draw_buffers WebGL extention support in command buffer.

content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_COMMON_GPU_CLIENT_WEBGRAPHICSCONTEXT3D_COMMAND_BUFFER_IMPL_H_
 #define CONTENT_COMMON_GPU_CLIENT_WEBGRAPHICSCONTEXT3D_COMMAND_BUFFER_IMPL_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 613 matching lines @@
       WGC3Dint level,
       WGC3Dint xoffset,
       WGC3Dint yoffset,
       WGC3Dsizei width,
       WGC3Dsizei height,
       WGC3Denum format,
       WGC3Denum type,
       const void* pixels);
   virtual void waitAsyncTexImage2DCHROMIUM(WGC3Denum target);
 
+  // GL_EXT_draw_buffers
+  virtual void drawBuffersEXT(
+      WGC3Dsizei n,
+      const WGC3Denum* bufs);
+
  protected:
   virtual GrGLInterface* onCreateGrGLInterface();
 
  private:
   // These are the same error codes as used by EGL.
   enum Error {
     SUCCESS               = 0x3000,
     BAD_ATTRIBUTE         = 0x3004,
     CONTEXT_LOST          = 0x300E
   };
@@ skipping 121 matching lines @@
   gpu::gles2::GLES2Interface* trace_gl_;
   Error last_error_;
   int frame_number_;
   bool bind_generates_resources_;
   bool use_echo_for_swap_ack_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_GPU_CLIENT_WEBGRAPHICSCONTEXT3D_COMMAND_BUFFER_IMPL_H_