Fix gpu mipmap support on ChromeOS

ui/gl/gl_version_info.h

 // Copyright 2014 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 UI_GL_GL_VERSION_INFO_H_
 #define UI_GL_GL_VERSION_INFO_H_
 
 #include <set>
 #include <string>
 #include "base/macros.h"
@@ skipping 30 matching lines @@
 
   static void ParseVersionString(const char* version_str,
                                  unsigned* major_version,
                                  unsigned* minor_version,
                                  bool* is_es,
                                  bool* is_es2,
                                  bool* is_es3);
 
   bool is_es;
   bool is_angle;
+  bool is_mesa;
   unsigned major_version;
   unsigned minor_version;
   bool is_es2;
   bool is_es3;
   bool is_desktop_core_profile;
   bool is_es3_capable;
 
  private:
   GLVersionInfo();
   void Initialize(const char* version_str,
                   const char* renderer_str,
                   const std::set<std::string>& extensions);
   bool IsES3Capable(const std::set<std::string>& extensions) const;
 
   DISALLOW_COPY_AND_ASSIGN(GLVersionInfo);
 };
 
 }  // namespace gl
 
 #endif // UI_GL_GL_VERSION_INFO_H_