Task Manager should listen to WebContentsObserver::RenderFrameCreated.

content/browser/renderer_host/render_process_host_impl.cc

 // Copyright 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 565 matching lines @@
     url_loader_factory_binding_.Bind(std::move(loader_request));
   }
 
  private:
   const int render_process_id_;
   mojo::AssociatedBinding<mojom::URLLoaderFactory> url_loader_factory_binding_;
 
   scoped_refptr<ServiceWorkerContextWrapper> service_worker_context_;
 };
 
+class RenderProcessHostIsReadyObserver : public RenderProcessHostObserver {
+ public:
+  RenderProcessHostIsReadyObserver(RenderProcessHost* render_process_host,
+                                   base::OnceClosure task)
+      : render_process_host_(render_process_host),
+        task_(std::move(task)),
+        weak_factory_(this) {
+    render_process_host_->AddObserver(this);
+    if (render_process_host_->IsReady())
+      PostTask();
+  }
+
+  ~RenderProcessHostIsReadyObserver() override {
+    render_process_host_->RemoveObserver(this);
+  }
+
+  void RenderProcessReady(RenderProcessHost* host) override { PostTask(); }
+
+  void RenderProcessHostDestroyed(RenderProcessHost* host) override {
+    delete this;
+  }
+
+ private:
+  void PostTask() {
+    BrowserThread::PostTask(
+        BrowserThread::UI, FROM_HERE,
+        base::Bind(&RenderProcessHostIsReadyObserver::CallTask,
+                   weak_factory_.GetWeakPtr()));
+  }
+
+  void CallTask() {
+    DCHECK_CURRENTLY_ON(BrowserThread::UI);
+    if (render_process_host_->IsReady())
+      std::move(task_).Run();
+
+    delete this;
+  }
+
+  RenderProcessHost* render_process_host_;
+  base::OnceClosure task_;
+  base::WeakPtrFactory<RenderProcessHostIsReadyObserver> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(RenderProcessHostIsReadyObserver);
+};
+
 }  // namespace
 
 RendererMainThreadFactoryFunction g_renderer_main_thread_factory = NULL;
 
 base::MessageLoop* g_in_process_thread;
 
 // Stores the maximum number of renderer processes the content module can
 // create.
 static size_t g_max_renderer_count_override = 0;
 
@@ skipping 2353 matching lines @@
   std::unique_ptr<RenderWidgetHostIterator> widgets(
       RenderWidgetHost::GetRenderWidgetHosts());
   while (RenderWidgetHost* widget = widgets->GetNextHost()) {
     // Count only RenderWidgetHosts in this process.
     if (widget->GetProcess()->GetID() == GetID())
       num_active_views++;
   }
   return num_active_views;
 }
 
+void RenderProcessHost::PostTaskWhenProcessIsReady(base::OnceClosure task) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  DCHECK(!task.is_null());
+  new RenderProcessHostIsReadyObserver(this, std::move(task));
+}
+
 void RenderProcessHostImpl::ReleaseOnCloseACK(
     RenderProcessHost* host,
     const SessionStorageNamespaceMap& sessions,
     int view_route_id) {
   DCHECK(host);
   if (sessions.empty())
     return;
   SessionStorageHolder* holder = static_cast<SessionStorageHolder*>(
       host->GetUserData(kSessionStorageHolderKey));
   if (!holder) {
@@ skipping 301 matching lines @@
   LOG(ERROR) << "Terminating render process for bad Mojo message: " << error;
 
   // The ReceivedBadMessage call below will trigger a DumpWithoutCrashing.
   // Capture the error message in a crash key value.
   base::debug::ScopedCrashKey error_key_value("mojo-message-error", error);
   bad_message::ReceivedBadMessage(render_process_id,
                                   bad_message::RPH_MOJO_PROCESS_ERROR);
 }
 
 }  // namespace content