Make checkdeps.py check third_party.

third_party/libjingle/overrides/allocator_shim/allocator_proxy.cc

 // Copyright 2013 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 "allocator_shim/allocator_stub.h"
+#include "third_party/libjingle/overrides/allocator_shim/allocator_stub.h"
 
 #if !defined(LIBPEERCONNECTION_IMPLEMENTATION) || defined(LIBPEERCONNECTION_LIB)
 #error "Only compile the allocator proxy with the shared_library implementation"
 #endif
 
 #if defined(OS_MACOSX) || defined(OS_ANDROID)
 #error "The allocator proxy isn't supported (or needed) on mac or android."
 #endif
 
 extern AllocateFunction g_alloc;
 extern DellocateFunction g_dealloc;
 
 // Override the global new/delete routines and proxy them over to the allocator
 // routines handed to us via InitializeModule.
 
 void* operator new(std::size_t n) throw() {
   return g_alloc(n);
 }
 
 void operator delete(void* p) throw() {
   g_dealloc(p);
 }