Make shared memory allocation possible for all child process types.

content/common/child_process_messages.h

 // Copyright (c) 2011 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.
 
 // Common IPC messages used for child processes.
 // Multiply-included message file, hence no include guard.
 
+#include "base/shared_memory.h"
 #include "content/common/content_export.h"
 #include "googleurl/src/gurl.h"
 #include "ipc/ipc_message_macros.h"
 
 #undef IPC_MESSAGE_EXPORT
 #define IPC_MESSAGE_EXPORT CONTENT_EXPORT
 
 #define IPC_MESSAGE_START ChildProcessMsgStart
 
 // Messages sent from the browser to the child process.
@@ skipping 53 matching lines @@
 
 #if defined(OS_WIN)
 // Request that the given font be loaded by the host so it's cached by the
 // OS. Please see ChildProcessHost::PreCacheFont for details.
 IPC_SYNC_MESSAGE_CONTROL1_0(ChildProcessHostMsg_PreCacheFont,
                             LOGFONT /* font data */)
 
 // Release the cached font
 IPC_MESSAGE_CONTROL0(ChildProcessHostMsg_ReleaseCachedFonts)
 #endif  // defined(OS_WIN)
+
+// Asks the browser to create a block of shared memory for the child process to
+// fill in and pass back to the browser.
+IPC_SYNC_MESSAGE_CONTROL1_1(ChildProcessHostMsg_SyncAllocateSharedMemory,
+                            size_t /* buffer size */,
+                            base::SharedMemoryHandle)