Fix gpu mipmap support on ChromeOS

ui/gl/gl_gl_api_implementation.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 "ui/gl/gl_gl_api_implementation.h"
 
 #include <vector>
 
 #include "base/command_line.h"
 #include "base/stl_util.h"
@@ skipping 18 matching lines @@
 // A GL Api that calls TRACE and then calls another GL api.
 static TraceGLApi* g_trace_gl = NULL;
 // The GL Api being used for stub contexts. If null, g_gl is used instead.
 static GLApi* g_stub_gl = NULL;
 // GL version used when initializing dynamic bindings.
 static GLVersionInfo* g_version_info = NULL;
 
 namespace {
 
 static inline GLenum GetInternalFormat(GLenum internal_format) {
-  if (GetGLImplementation() != kGLImplementationEGLGLES2) {
+  if (!g_version_info->is_es) {
     if (internal_format == GL_BGRA_EXT || internal_format == GL_BGRA8_EXT)
       return GL_RGBA8;
   }
+  if (g_version_info->is_es3 && g_version_info->is_mesa) {
+    // Mesa bug workaround: Mipmapping does not work when using GL_BGRA_EXT
+    if (internal_format == GL_BGRA_EXT)
+      return GL_RGBA;
+  }
   return internal_format;
 }
 
 // TODO(epenner): Could the above function be merged into this and removed?
 static inline GLenum GetTexInternalFormat(GLenum internal_format,
                                           GLenum format,
                                           GLenum type) {
+  DCHECK(g_version_info);
   GLenum gl_internal_format = GetInternalFormat(internal_format);
 
   // g_version_info must be initialized when this function is bound.
-  DCHECK(g_version_info);
   if (g_version_info->is_es3) {
     if (internal_format == GL_RED_EXT) {
       // GL_EXT_texture_rg case in ES2.
       switch (type) {
         case GL_UNSIGNED_BYTE:
           gl_internal_format = GL_R8_EXT;
           break;
         case GL_HALF_FLOAT_OES:
           gl_internal_format = GL_R16F_EXT;
           break;
@@ skipping 499 matching lines @@
 TraceGLApi::~TraceGLApi() {
 }
 
 NoContextGLApi::NoContextGLApi() {
 }
 
 NoContextGLApi::~NoContextGLApi() {
 }
 
 }  // namespace gl