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

ppapi/c/dev/ppb_graphics_3d_dev.h

 /* 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.
  */
 #ifndef PPAPI_C_DEV_PPB_GRAPHICS_3D_DEV_H_
 #define PPAPI_C_DEV_PPB_GRAPHICS_3D_DEV_H_
 
 #include "ppapi/c/pp_bool.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_module.h"
@@ skipping 60 matching lines @@
   // another thread leads to undefined behavior.
   PP_Resource (*CreateContext)(PP_Instance instance,
                                int32_t config,
                                int32_t share_context,
                                const int32_t* attrib_list);
 
   // Get the address of any GL functions, whether core or part of an extension.
   // Any thread.
   void* (*GetProcAddress)(const char* name);
 
-  // Make a particular context current of the calling thread.  Returns PP_TRUE
-  // on success, PP_FALSE on failure.
-  PP_Bool (*MakeCurent)(PP_Resource context);
-
-  // Returns the calling thread's current context or NULL if no context is
-  // current.
-  PP_Resource (*GetCurrentContext)();
-
   // Snapshots the rendered frame and makes it available for composition with
   // the rest of the page. The alpha channel is used for translucency effects.
   // One means fully opaque. Zero means fully transparent. Any thread.
   // TODO(apatrick): premultiplied alpha or linear alpha? Premultiplied alpha is
   // better for correct alpha blending effect. Most existing OpenGL code assumes
   // linear. I could convert from linear to premultiplied during the copy from
   // back-buffer to offscreen "front-buffer".
   PP_Bool (*SwapBuffers)(PP_Resource context);
 
   // Returns the current error for this thread. This is not associated with a
   // particular context. It is distinct from the GL error returned by
   // glGetError.
   uint32_t (*GetError)();
 };
 
 #endif  /* PPAPI_C_DEV_PPB_GRAPHICS_3D_DEV_H_ */