Remove DeferBackgroundExtensionCreation field trial and supporting code

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 95 matching lines @@
 
   // Tracks network requests for a given RenderViewHost, used to know
   // when network activity is idle for lazy background pages.
   void OnNetworkRequestStarted(content::RenderViewHost* render_view_host);
   void OnNetworkRequestDone(content::RenderViewHost* render_view_host);
 
   // Prevents |extension|'s background page from being closed and sends the
   // onSuspendCanceled() event to it.
   void CancelSuspend(const Extension* extension);
 
-  // If |defer| is true background host creation is to be deferred until this is
-  // called again with |defer| set to false, at which point all deferred
-  // background hosts will be created.  Defaults to false.
-  void DeferBackgroundHostCreation(bool defer);
-
   // Ensures background hosts are loaded for a new browser window.
   void OnBrowserWindowReady();
 
   // Gets the BrowserContext associated with site_instance_ and all other
   // related SiteInstances.
   content::BrowserContext* GetBrowserContext() const;
 
  protected:
   // If |context| is incognito pass the master context as |original_context|.
   // Otherwise pass the same context for both.
@@ skipping 77 matching lines @@
   BackgroundPageDataMap background_page_data_;
 
   // The time to delay between an extension becoming idle and
   // sending a ShouldSuspend message; read from command-line switch.
   base::TimeDelta event_page_idle_time_;
 
   // The time to delay between sending a ShouldSuspend message and
   // sending a Suspend message; read from command-line switch.
   base::TimeDelta event_page_suspending_time_;
 
-  // If true, then creation of background hosts is suspended.
-  bool defer_background_host_creation_;
-
   // True if we have created the startup set of background hosts.
   bool startup_background_hosts_created_;
 
   base::Callback<void(content::DevToolsAgentHost*, bool)> devtools_callback_;
 
   base::WeakPtrFactory<ProcessManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ProcessManager);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_PROCESS_MANAGER_H_