Update gl2.h and gl2ext.h headers from Khronos.

ppapi/native_client/src/shared/ppapi_proxy/browser_ppp.cc

 // Copyright (c) 2012 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 "native_client/src/shared/ppapi_proxy/browser_ppp.h"
 
 #include <string.h>
 
 #include "native_client/src/include/nacl_scoped_ptr.h"
 #include "native_client/src/include/portability.h"
@@ skipping 151 matching lines @@
   is_nexe_alive_ = (srpc_result != NACL_SRPC_RESULT_INTERNAL);
 
   // Special case PPP_Instance versioning. The plugin side of the proxy
   // converts Instance 1.1 to Instance 1.0 as needed, so we want to say here
   // in the browser side that any time either 1.0 or 1.1 is supported, that
   // we'll support 1.1.
   if (srpc_result == NACL_SRPC_RESULT_OK && !exports_interface_name &&
       strcmp(interface_name, PPP_INSTANCE_INTERFACE_1_1) == 0) {
     srpc_result =
         PppRpcClient::PPP_GetInterface(main_channel_,
-                                       PPP_INSTANCE_INTERFACE_1_0,
-                                       &exports_interface_name);
+            const_cast<char *>(PPP_INSTANCE_INTERFACE_1_0),
+            &exports_interface_name);
   }
 
   const void* ppp_interface = NULL;
   if (srpc_result != NACL_SRPC_RESULT_OK || !exports_interface_name) {
     ppp_interface = NULL;
   } else if (strcmp(interface_name, PPP_INSTANCE_INTERFACE) == 0) {
     ppp_interface =
        reinterpret_cast<const void*>(BrowserInstance::GetInterface());
   } else if (strcmp(interface_name, PPP_MESSAGING_INTERFACE) == 0) {
     ppp_interface =
@@ skipping 30 matching lines @@
 
 const void* BrowserPpp::GetPluginInterfaceSafe(const char* interface_name) {
   const void* ppp_interface = GetPluginInterface(interface_name);
   if (ppp_interface == NULL)
     DebugPrintf("PPB_GetInterface: %s not found\n", interface_name);
   CHECK(ppp_interface != NULL);
   return ppp_interface;
 }
 
 }  // namespace ppapi_proxy