Revert of Fix ReadPixels from float fbo buffer in ES2/WebGL1.

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 37 matching lines @@
     if (IsAtLeastGL(3, 2))
       return true;
 #endif
     return false;
   }
 
   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;
   unsigned major_version;
   unsigned minor_version;
-  bool is_es2;
   bool is_es3;
   bool is_desktop_core_profile;
 
  private:
   GLVersionInfo(const char* version_str, const char* renderer_str);
 
   DISALLOW_COPY_AND_ASSIGN(GLVersionInfo);
 };
 
 }  // namespace gfx
 
 #endif // UI_GL_GL_VERSION_INFO_H_