Implement EXT_draw_buffers WebGL extention support in command buffer.

gpu/command_buffer/common/gles2_cmd_utils.cc

 // 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.
 
 // This file is here so other GLES2 related files can have a common set of
 // includes where appropriate.
 
 #include <stdio.h>
 #include <GLES2/gl2.h>
 #include <GLES2/gl2ext.h>
@@ skipping 607 matching lines @@
     case GL_DEPTH24_STENCIL8_OES:
       return kDepth | kStencil;
     default:
       return 0x0000;
   }
 }
 
 uint32 GLES2Util::GetChannelsNeededForAttachmentType(int type) {
   switch (type) {
     case GL_COLOR_ATTACHMENT0:
+    case GL_COLOR_ATTACHMENT1_EXT:
+    case GL_COLOR_ATTACHMENT2_EXT:
+    case GL_COLOR_ATTACHMENT3_EXT:
+    case GL_COLOR_ATTACHMENT4_EXT:
+    case GL_COLOR_ATTACHMENT5_EXT:
+    case GL_COLOR_ATTACHMENT6_EXT:
+    case GL_COLOR_ATTACHMENT7_EXT:
+    case GL_COLOR_ATTACHMENT8_EXT:
+    case GL_COLOR_ATTACHMENT9_EXT:
+    case GL_COLOR_ATTACHMENT10_EXT:
+    case GL_COLOR_ATTACHMENT11_EXT:
+    case GL_COLOR_ATTACHMENT12_EXT:
+    case GL_COLOR_ATTACHMENT13_EXT:
+    case GL_COLOR_ATTACHMENT14_EXT:
+    case GL_COLOR_ATTACHMENT15_EXT:
       return kRGBA;
     case GL_DEPTH_ATTACHMENT:
       return kDepth;
     case GL_STENCIL_ATTACHMENT:
       return kStencil;
     default:
       return 0x0000;
   }
 }
 
@@ skipping 154 matching lines @@
   }
 
   return true;
 }
 
 #include "../common/gles2_cmd_utils_implementation_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu