Control process backgrounding from within the child process on Windows.

content/browser/renderer_host/render_process_host_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.
 
 // Represents the browser side of the browser <--> renderer communication
 // channel. There will be one RenderProcessHost per renderer process.
 
 #include "content/browser/renderer_host/render_process_host_impl.h"
 
 #include <algorithm>
@@ skipping 1929 matching lines @@
 
 #if defined(OS_WIN)
   // The cbstext.dll loads as a global GetMessage hook in the browser process
   // and intercepts/unintercepts the kernel32 API SetPriorityClass in a
   // background thread. If the UI thread invokes this API just when it is
   // intercepted the stack is messed up on return from the interceptor
   // which causes random crashes in the browser process. Our hack for now
   // is to not invoke the SetPriorityClass API if the dll is loaded.
   if (GetModuleHandle(L"cbstext.dll"))
     return;
+
+  // Windows Vista+ has a fancy process backgrounding mode that can only be set
+  // from within the process.  So notify the child process of background state.
+  Send(new ChildProcessMsg_SetProcessBackgrounded(backgrounded));
+#else
+
+  // Backgrounding may require elevated privileges not available to renderer
+  // processes, so control backgrounding from the process host.
+  child_process_launcher_->SetProcessBackgrounded(backgrounded);
 #endif  // OS_WIN
-
-  child_process_launcher_->SetProcessBackgrounded(backgrounded);
 }
 
 void RenderProcessHostImpl::OnProcessLaunched() {
   // No point doing anything, since this object will be destructed soon.  We
   // especially don't want to send the RENDERER_PROCESS_CREATED notification,
   // since some clients might expect a RENDERER_PROCESS_TERMINATED afterwards to
   // properly cleanup.
   if (deleting_soon_)
     return;
 
   if (child_process_launcher_) {
     if (!child_process_launcher_->GetHandle()) {
       OnChannelError();
       return;
     }
 
-    child_process_launcher_->SetProcessBackgrounded(backgrounded_);
+    SetBackgrounded(backgrounded_);
   }
 
   // NOTE: This needs to be before sending queued messages because
   // ExtensionService uses this notification to initialize the renderer process
   // with state that must be there before any JavaScript executes.
   //
   // The queued messages contain such things as "navigate". If this notification
   // was after, we can end up executing JavaScript before the initialization
   // happens.
   NotificationService::current()->Notify(
@@ skipping 93 matching lines @@
     mojo::ScopedMessagePipeHandle handle) {
   mojo_activation_required_ = true;
   MaybeActivateMojo();
 
   mojo::AllocationScope scope;
   mojo_application_host_->service_provider()->ConnectToService(service_name,
                                                                handle.Pass());
 }
 
 }  // namespace content