ResourceScheduler should use renderer notifications instead of MRUCache to track renderers.

content/browser/loader/resource_scheduler_view_observer.cc

+// Copyright (c) 2013 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/browser/loader/resource_scheduler_view_observer.h"
+
+#include "content/browser/loader/resource_dispatcher_host_impl.h"
+#include "content/browser/loader/resource_scheduler.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/notification_service.h"
+#include "content/public/browser/notification_types.h"
+#include "content/public/browser/render_process_host.h"
+#include "content/public/browser/render_view_host.h"
+
+namespace content {
+
+ResourceSchedulerViewObserver::ResourceSchedulerViewObserver() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  registrar_.Add(this, NOTIFICATION_RENDER_VIEW_HOST_CREATED,
+                 NotificationService::AllSources());
+  registrar_.Add(this, NOTIFICATION_RENDER_VIEW_HOST_DELETED,
+                 NotificationService::AllSources());
+}
+
+ResourceSchedulerViewObserver::~ResourceSchedulerViewObserver() {

[darin (slow to review), 2013/03/13 00:12:27]

do we need to make sure that this class is destroyed on the UI thread too?  oh,
it looks like NotificationRegistrar takes care of that for us.

+}
+
+void OnRenderViewHostCreated(int child_id, int route_id) {

[darin (slow to review), 2013/03/13 00:12:27]

nit: these methods should be static or in an anon namespace.

+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  ResourceDispatcherHostImpl::Get()->scheduler()->OnClientCreated(
+      child_id, route_id);
+}
+
+void OnRenderViewHostDestroyed(int child_id, int route_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  ResourceDispatcherHostImpl::Get()->scheduler()->OnClientDestroyed(
+      child_id, route_id);
+}
+
+void ResourceSchedulerViewObserver::Observe(
+    int type,
+    const NotificationSource& source,
+    const NotificationDetails& details) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  RenderViewHost* rvh = content::Source<RenderViewHost>(source).ptr();
+  int child_id = rvh->GetProcess()->GetID();
+  int route_id = rvh->GetRoutingID();
+
+  switch (type) {
+    case NOTIFICATION_RENDER_VIEW_HOST_CREATED:
+      BrowserThread::PostTask(
+          BrowserThread::IO, FROM_HERE,
+          base::Bind(&OnRenderViewHostCreated, child_id, route_id));
+      break;
+
+    case NOTIFICATION_RENDER_VIEW_HOST_DELETED:
+      BrowserThread::PostTask(
+          BrowserThread::IO, FROM_HERE,
+          base::Bind(&OnRenderViewHostDestroyed, child_id, route_id));
+      break;
+  }
+}
+
+}  // namespace content