Moved the logic of maintaining the current context to gles2 helper library.

ppapi/ppapi.gyp

 # Copyright (c) 2010 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.
 
 {
   'includes': [
     '../third_party/mesa/mesa.gypi',
   ],
   'variables': {
     'chromium_code': 1,  # Use higher warning level.
@@ skipping 104 matching lines @@
       ],
     },
     {
       'target_name': 'ppapi_cpp_objects',
       'type': 'static_library',
       'dependencies': [
         'ppapi_c'
       ],
       'include_dirs': [
         '..',
+        'lib/gl/include',
       ],
       'sources': [
         'cpp/common.h',
         'cpp/completion_callback.h',
         'cpp/core.cc',
         'cpp/core.h',
         'cpp/graphics_2d.cc',
         'cpp/graphics_2d.h',
         'cpp/image_data.cc',
         'cpp/image_data.h',
@@ skipping 535 matching lines @@
         ['OS=="win"', {
         }],
         ['OS=="linux"', {
         }],
         ['OS=="mac"', {
         }]
       ],
     },
   ],
 }