Stop disabling force_compositing_mode for background RenderViews.

chrome/browser/tab_contents/background_contents.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 "chrome/browser/tab_contents/background_contents.h"
 
 #include "chrome/browser/background/background_contents_service.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/chrome_extension_web_contents_observer.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 15 matching lines @@
     SiteInstance* site_instance,
     int routing_id,
     Delegate* delegate,
     const std::string& partition_id,
     content::SessionStorageNamespace* session_storage_namespace)
     : delegate_(delegate) {
   profile_ = Profile::FromBrowserContext(
       site_instance->GetBrowserContext());
 
   WebContents::CreateParams create_params(profile_, site_instance);
+  create_params.initially_hidden = true;
   create_params.routing_id = routing_id;
   if (session_storage_namespace) {
     content::SessionStorageNamespaceMap session_storage_namespace_map;
     session_storage_namespace_map.insert(
         std::make_pair(partition_id, session_storage_namespace));
     web_contents_.reset(WebContents::CreateWithSessionStorage(
         create_params, session_storage_namespace_map));
   } else {
     web_contents_.reset(WebContents::Create(create_params));
   }
@@ skipping 70 matching lines @@
 void BackgroundContents::AddNewContents(WebContents* source,
                                         WebContents* new_contents,
                                         WindowOpenDisposition disposition,
                                         const gfx::Rect& initial_pos,
                                         bool user_gesture,
                                         bool* was_blocked) {
   delegate_->AddWebContents(
       new_contents, disposition, initial_pos, user_gesture, was_blocked);
 }
 
+bool BackgroundContents::IsWebContentsNeverVisible(
+    content::WebContents* web_contents) {
+  DCHECK_EQ(extensions::VIEW_TYPE_BACKGROUND_CONTENTS,
+            extensions::GetViewType(web_contents));

[jam, 2014/04/14 22:43:01]

this seems like a redundant dcheck. i would prefer we take it out. i.e. if we
can't trust that random code isn't changing the view type of webcontents in
chrome, then all hope is lost.

[danakj, 2014/04/14 22:47:30]

To me it's not so much about trust but to document the expectations of this
function and why it can return true, in a way that will have to be updated if
things changed in the future. I'd prefer to keep it if you don't feel strongly
about removing it.

+  return true;
+}
+
 void BackgroundContents::RenderProcessGone(base::TerminationStatus status) {
   content::NotificationService::current()->Notify(
       chrome::NOTIFICATION_BACKGROUND_CONTENTS_TERMINATED,
       content::Source<Profile>(profile_),
       content::Details<BackgroundContents>(this));
 
   // Our RenderView went away, so we should go away also, so killing the process
   // via the TaskManager doesn't permanently leave a BackgroundContents hanging
   // around the system, blocking future instances from being created
   // <http://crbug.com/65189>.
   delete this;
 }
 
 void BackgroundContents::Observe(int type,
                                  const content::NotificationSource& source,
                                  const content::NotificationDetails& details) {
   // TODO(rafaelw): Implement pagegroup ref-counting so that non-persistent
   // background pages are closed when the last referencing frame is closed.
   switch (type) {
     case chrome::NOTIFICATION_PROFILE_DESTROYED:
     case chrome::NOTIFICATION_APP_TERMINATING: {
       delete this;
       break;
     }
     default:
       NOTREACHED() << "Unexpected notification sent.";
       break;
   }
 }