Use a direct include of strings headers in content/renderer and content/shell.

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 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 "content/renderer/gpu/render_widget_compositor.h"
 
 #include <limits>
 #include <string>
 
 #include "base/command_line.h"
 #include "base/logging.h"
-#include "base/string_number_conversions.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/synchronization/lock.h"
 #include "base/time.h"
 #include "cc/base/switches.h"
 #include "cc/base/thread_impl.h"
 #include "cc/debug/layer_tree_debug_state.h"
 #include "cc/layers/layer.h"
 #include "cc/trees/layer_tree_host.h"
 #include "content/common/gpu/client/context_provider_command_buffer.h"
 #include "content/public/common/content_switches.h"
 #include "content/renderer/gpu/input_handler_manager.h"
@@ skipping 546 matching lines @@
   return RenderThreadImpl::current()->OffscreenContextProviderForMainThread();
 }
 
 scoped_refptr<cc::ContextProvider>
 RenderWidgetCompositor::OffscreenContextProviderForCompositorThread() {
   return RenderThreadImpl::current()->
       OffscreenContextProviderForCompositorThread();
 }
 
 }  // namespace content