Revert of Removing the ChildProcessHostMsg_SyncAllocateSharedMemory IPC message.

content/browser/renderer_host/render_message_filter.h

Index: content/browser/renderer_host/render_message_filter.h
diff --git a/content/browser/renderer_host/render_message_filter.h b/content/browser/renderer_host/render_message_filter.h
index 99fcd059a1cba0e16d4b3c02599ecfc1123a9dc7..1aa79618ab91d17918a38927b6edf68e2aad993e 100644
--- a/content/browser/renderer_host/render_message_filter.h
+++ b/content/browser/renderer_host/render_message_filter.h
@@ -149,6 +149,9 @@
   // Used to ask the browser to allocate a block of shared memory for the
   // renderer to send back data in, since shared memory can't be created
   // in the renderer on POSIX due to the sandbox.
+  void AllocateSharedMemoryOnFileThread(uint32_t buffer_size,
+                                        IPC::Message* reply_msg);
+  void OnAllocateSharedMemory(uint32_t buffer_size, IPC::Message* reply_msg);
   void AllocateSharedBitmapOnFileThread(uint32_t buffer_size,
                                         const cc::SharedBitmapId& id,
                                         IPC::Message* reply_msg);