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

ppapi/lib/gl/gles2/gl2ext_ppapi.c

 // 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.
 
 #include "ppapi/lib/gl/gles2/gl2ext_ppapi.h"
 
-static const struct PPB_OpenGLES_Dev* g_gles2_interface;
+#ifndef GL_FALSE
+#define GL_FALSE 0
+#endif  // GL_FALSE
 
-int GL_APIENTRY glInitializePPAPI(
-    PP_Module module,
+#ifndef GL_TRUE
+#define GL_TRUE 1
+#endif  // GL_TRUE
+
+#if defined(__GNUC__) && !defined(__APPLE__)
+#define PP_TLS __thread
+#elif defined(_MSC_VER)
+#define PP_TLS __declspec(thread)
+#else
+// TODO(alokp): Fix all other platforms.
+#define PP_TLS
+#endif
+
+// TODO(alokp): This will need to be thread-safe if we build gles2 as a
+// shared library.
+static const struct PPB_OpenGLES2_Dev* g_gles2_interface = NULL;
+
+// TODO(alokp): Make sure PP_TLS works on all supported platforms.
+static PP_TLS PP_Resource g_current_context = 0;
+
+GLboolean GL_APIENTRY glInitializePPAPI(
     PPB_GetInterface get_browser_interface) {
-  return 0;
+  if (!g_gles2_interface) {
+    g_gles2_interface = get_browser_interface(PPB_OPENGLES2_DEV_INTERFACE);
+  }
+  return g_gles2_interface ? GL_TRUE : GL_FALSE;
 }
 
-int GL_APIENTRY glTerminatePPAPI() {
-  return 0;
+GLboolean GL_APIENTRY glTerminatePPAPI() {
+  g_gles2_interface = NULL;
+  return GL_TRUE;
 }
 
 void GL_APIENTRY glSetCurrentContextPPAPI(PP_Resource context) {
+  g_current_context = context;
 }
 
 PP_Resource GL_APIENTRY glGetCurrentContextPPAPI() {
-  return 0;
+  return g_current_context;
 }
 
-const struct PPB_OpenGLES_Dev* GL_APIENTRY glGetInterfacePPAPI() {
+const struct PPB_OpenGLES2_Dev* GL_APIENTRY glGetInterfacePPAPI() {
   return g_gles2_interface;
 }