Update GL_IMPLEMENTATION_COLOR_READ_FORMAT for BGRA

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 <sstream>
 #include <GLES2/gl2.h>
 #include <GLES2/gl2ext.h>
@@ skipping 961 matching lines @@
       return 4;
     case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z:
       return 5;
     default:
       NOTREACHED();
       return 0;
   }
 }
 
 uint32_t GLES2Util::GetGLReadPixelsImplementationFormat(
-    uint32_t internal_format) {
+    uint32_t internal_format,
+    uint32_t texture_type,
+    bool supports_bgra) {

[ericrk, 2016/03/07 20:38:59]

could pass the context in as well (and have the extension querying internal to
this fn), but that requires dependency changes.

   switch (internal_format) {
     case GL_R8:
     case GL_R16F:
     case GL_R32F:
       return GL_RED;
     case GL_R8UI:
     case GL_R8I:
     case GL_R16UI:
     case GL_R16I:
     case GL_R32UI:
@@ skipping 18 matching lines @@
     case GL_RGB32F:
       return GL_RGB;
     case GL_RGBA8UI:
     case GL_RGBA8I:
     case GL_RGB10_A2UI:
     case GL_RGBA16UI:
     case GL_RGBA16I:
     case GL_RGBA32UI:
     case GL_RGBA32I:
       return GL_RGBA_INTEGER;
+    case GL_BGRA_EXT:
+    case GL_BGRA8_EXT:
+      // If the internal format is BGRA, we prefer reading back BGRA if
+      // possible.
+      if (texture_type == GL_UNSIGNED_BYTE && supports_bgra)
+        return GL_BGRA_EXT;
+      else
+        return GL_RGBA;
     default:
       return GL_RGBA;
   }
 }
 
 uint32_t GLES2Util::GetGLReadPixelsImplementationType(uint32_t internal_format,
                                                       uint32_t texture_type) {
   switch (internal_format) {
     case GL_R16UI:
     case GL_RG16UI:
@@ skipping 498 matching lines @@
   }
 
   return true;
 }
 
 #include "gpu/command_buffer/common/gles2_cmd_utils_implementation_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu