Refactor code that defers extension background page loading

extensions/browser/process_manager.h

 // Copyright 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.
 
 #ifndef EXTENSIONS_BROWSER_PROCESS_MANAGER_H_
 #define EXTENSIONS_BROWSER_PROCESS_MANAGER_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 17 matching lines @@
 class RenderFrameHost;
 class SiteInstance;
 };
 
 namespace extensions {
 
 class Extension;
 class ExtensionHost;
 class ProcessManagerObserver;
 
+// Customization of ProcessManager from the extension system embedder.
+class ProcessManagerDelegate {

[Yoyo Zhou, 2014/07/15 02:13:22]

Probably it's best to put this in a separate header file.

[James Cook, 2014/07/15 17:02:52]

Done.

+ public:
+  virtual ~ProcessManagerDelegate() {}
+
+  // Returns true if the embedder allows background pages for the given
+  // |context|.
+  virtual bool IsBackgroundPageAllowed(
+      content::BrowserContext* context) const = 0;
+
+  // Returns true if the embedder wishes to defer starting up the renderers for
+  // extension background pages. If the embedder returns true it must call
+  // ProcessManager::MaybeCreateStartupBackgroundHosts() when it is ready. See
+  // ChromeProcessManagerDelegate for examples of how this is useful.
+  virtual bool DeferCreatingStartupBackgroundHosts(
+      content::BrowserContext* context) const = 0;
+};
+
 // Manages dynamic state of running Chromium extensions. There is one instance
 // of this class per Profile. OTR Profiles have a separate instance that keeps
 // track of split-mode extensions only.
 class ProcessManager : public content::NotificationObserver {
  public:
   typedef std::set<extensions::ExtensionHost*> ExtensionHostSet;
   typedef ExtensionHostSet::const_iterator const_iterator;
 
   static ProcessManager* Create(content::BrowserContext* context);
   virtual ~ProcessManager();
@@ skipping 67 matching lines @@
 
   // Tracks network requests for a given RenderFrameHost, used to know
   // when network activity is idle for lazy background pages.
   void OnNetworkRequestStarted(content::RenderFrameHost* render_frame_host);
   void OnNetworkRequestDone(content::RenderFrameHost* render_frame_host);
 
   // Prevents |extension|'s background page from being closed and sends the
   // onSuspendCanceled() event to it.
   void CancelSuspend(const Extension* extension);
 
-  // Ensures background hosts are loaded for a new browser window.
-  void OnBrowserWindowReady();
+  // Creates background hosts if the embedder is ready and they are not already
+  // loaded.
+  void MaybeCreateStartupBackgroundHosts();
 
   // Gets the BrowserContext associated with site_instance_ and all other
   // related SiteInstances.
   content::BrowserContext* GetBrowserContext() const;
 
   // Sets callbacks for testing keepalive impulse behavior.
   typedef base::Callback<void(const std::string& extension_id)>
       ImpulseCallbackForTesting;
   void SetKeepaliveImpulseCallbackForTesting(
       const ImpulseCallbackForTesting& callback);
   void SetKeepaliveImpulseDecrementCallbackForTesting(
       const ImpulseCallbackForTesting& callback);
 
   // Creates an incognito-context instance for tests. Tests for non-incognito
   // contexts can just use Create() above.
   static ProcessManager* CreateIncognitoForTesting(
       content::BrowserContext* incognito_context,
       content::BrowserContext* original_context,
       ProcessManager* original_manager);
 
+  bool startup_background_hosts_created_for_test() const {
+    return startup_background_hosts_created_;
+  }
+
  protected:
   // If |context| is incognito pass the master context as |original_context|.
   // Otherwise pass the same context for both.
   ProcessManager(content::BrowserContext* context,
                  content::BrowserContext* original_context);
 
   // Called on browser shutdown to close our extension hosts.
   void CloseBackgroundHosts();
 
   // content::NotificationObserver:
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
   // Load all background pages once the profile data is ready and the pages
   // should be loaded.
-  void CreateBackgroundHostsForProfileStartup();
+  void CreateStartupBackgroundHosts();

[Yoyo Zhou, 2014/07/15 02:13:22]

nit: does this need to be protected? can it be in private?

[James Cook, 2014/07/15 17:02:52]

Good catch! Moved to private.

 
   content::NotificationRegistrar registrar_;
 
   // The set of ExtensionHosts running viewless background extensions.
   ExtensionHostSet background_hosts_;
 
   // A SiteInstance related to the SiteInstance for all extensions in
   // this profile.  We create it in such a way that a new
   // browsing instance is created.  This controls process grouping.
   scoped_refptr<content::SiteInstance> site_instance_;
@@ skipping 35 matching lines @@
   // with an extension).
   bool RegisterRenderViewHost(content::RenderViewHost* render_view_host);
 
   // Unregister RenderViewHosts and clear background page data for an extension
   // which has been unloaded.
   void UnregisterExtension(const std::string& extension_id);
 
   // Clears background page data for this extension.
   void ClearBackgroundPageData(const std::string& extension_id);
 
-  // Returns true if loading background pages should be deferred.
-  bool DeferLoadingBackgroundHosts() const;
-
   void OnDevToolsStateChanged(content::DevToolsAgentHost*, bool attached);
 
   // Contains all active extension-related RenderViewHost instances for all
   // extensions. We also keep a cache of the host's view type, because that
   // information is not accessible at registration/deregistration time.
   ExtensionRenderViews all_extension_views_;
 
   BackgroundPageDataMap background_page_data_;
 
   // The time to delay between an extension becoming idle and
@@ skipping 15 matching lines @@
   ObserverList<ProcessManagerObserver> observer_list_;
 
   base::WeakPtrFactory<ProcessManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ProcessManager);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_PROCESS_MANAGER_H_