Update GL_IMPLEMENTATION_COLOR_READ_FORMAT for BGRA

gpu/command_buffer/service/gles2_cmd_decoder.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.
 
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
 
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
@@ skipping 5096 matching lines @@
         // internal implementation.
         if (params) {
           if (context_->HasExtension("GL_OES_read_format")) {
             ScopedGLErrorSuppressor suppressor("GLES2DecoderImpl::GetHelper",
                                                GetErrorState());
             glGetIntegerv(pname, params);
             if (glGetError() == GL_NO_ERROR)
               return true;
           }
           *params = GLES2Util::GetGLReadPixelsImplementationFormat(
-              GetBoundReadFrameBufferInternalFormat());
+              GetBoundReadFrameBufferInternalFormat(),
+              GetBoundReadFrameBufferTextureType(),
+              context_->HasExtension("GL_EXT_read_format_bgra"));

[piman, 2016/03/07 21:04:14]

Actually, here you're only asking the underlying GL context, not what we expose
to the client. That is, you'd pass false on desktop GL, when you'd want to pass
true.

My suggestion is to add a ext_read_format_bgra field in
FeatureInfo::FeatureFlags, that would be set in feature_info.cc where we enable
the extension (similar to, e.g. ext_texture_format_bgra8888) and use that here.

[ericrk, 2016/03/08 00:07:18]

ah, yeah, missed that - thanks! Added this to a feature flag and updated.

         }
         return true;
       case GL_IMPLEMENTATION_COLOR_READ_TYPE:
         *num_written = 1;
         if (params) {
           if (context_->HasExtension("GL_OES_read_format")) {
             ScopedGLErrorSuppressor suppressor("GLES2DecoderImpl::GetHelper",
                                                GetErrorState());
             glGetIntegerv(pname, params);
             if (glGetError() == GL_NO_ERROR)
@@ skipping 10822 matching lines @@
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "base/macros.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu