Renderer process can allocate anonymous shared memory without help from browser process on Windows.

content/renderer/pepper/pepper_plugin_delegate_impl.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 "content/renderer/pepper/pepper_plugin_delegate_impl.h"
 
 #include <cmath>
 #include <cstddef>
 #include <map>
 #include <queue>
@@ skipping 1365 matching lines @@
     const GURL& plugin_url) {
   PP_FlashLSORestrictions restrictions = PP_FLASHLSORESTRICTIONS_NONE;
   render_view_->Send(
       new PepperMsg_GetLocalDataRestrictions(document_url, plugin_url,
                                              &restrictions));
   return restrictions;
 }
 
 base::SharedMemory* PepperPluginDelegateImpl::CreateAnonymousSharedMemory(
     uint32_t size) {
-  if (size == 0)
-    return NULL;
-  base::SharedMemoryHandle handle;
-  if (!render_view_->Send(
-          new ChildProcessHostMsg_SyncAllocateSharedMemory(size, &handle))) {
-    DLOG(WARNING) << "Browser allocation request message failed";
-    return NULL;
-  }
-  if (!base::SharedMemory::IsHandleValid(handle)) {
-    DLOG(WARNING) << "Browser failed to allocate shared memory";
-    return NULL;
-  }
-  return new base::SharedMemory(handle, false);
+  return RenderThread::Get()->HostAllocateSharedMemoryBuffer(size).release();
 }
 
 ppapi::Preferences PepperPluginDelegateImpl::GetPreferences() {
   return ppapi::Preferences(render_view_->webkit_preferences());
 }
 
 bool PepperPluginDelegateImpl::LockMouse(
     webkit::ppapi::PluginInstance* instance) {
   return GetMouseLockDispatcher(instance)->LockMouse(
       GetOrCreateLockTargetAdapter(instance));
@@ skipping 338 matching lines @@
     RenderWidgetFullscreenPepper* container =
         static_cast<RenderWidgetFullscreenPepper*>(
             instance->fullscreen_container());
     return container->mouse_lock_dispatcher();
   } else {
     return render_view_->mouse_lock_dispatcher();
   }
 }
 
 }  // namespace content