Added pglGetCurrentContext. Make gles2 implementation pointer global variable...

gpu/pgl/pgl.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 GPU_PGL_PGL_H
 #define GPU_PGL_PGL_H
 
 #include "npapi.h"
 #include "npapi_extensions.h"
 
+#ifdef __cplusplus
 extern "C" {
+#endif
+
 typedef void* PGLContext;
 typedef bool PGLBoolean;
 
+// Create A PGL context from a Pepper 3D device context.
 PGLContext pglCreateContext(NPP npp,
                             NPDevice* device,
                             NPDeviceContext3D* device_context);
+
+// Set the current PGL context for the calling thread.
 PGLBoolean pglMakeCurrent(PGLContext pgl_context);
-PGLBoolean pglSwapBuffers();
+
+// Get the calling thread's current PGL context.
+PGLContext pglGetCurrentContext(void);
+
+// Display everything that has been rendered since the last call.
+PGLBoolean pglSwapBuffers(void);
+
+// Destroy the given PGL context.
 PGLBoolean pglDestroyContext(PGLContext pgl_context);
+
+#ifdef __cplusplus
 }  // extern "C"
+#endif
 
 #endif  // GPU_PGL_PGL_H