Only set precache.last_time when precache ran.

components/precache/content/precache_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 COMPONENTS_PRECACHE_CONTENT_PRECACHE_MANAGER_H_
 #define COMPONENTS_PRECACHE_CONTENT_PRECACHE_MANAGER_H_
 
 #include <list>
 #include <string>
 #include <utility>
@@ skipping 36 matching lines @@
 // BrowserContext that it is constructed for. Use
 // PrecacheManagerFactory::GetForBrowserContext to get an instance of this
 // class. All methods must be called on the UI thread unless indicated
 // otherwise.
 // TODO(sclittle): Delete precache history when browsing history is deleted.
 // http://crbug.com/326549
 class PrecacheManager : public KeyedService,
                         public PrecacheFetcher::PrecacheDelegate,
                         public base::SupportsWeakPtr<PrecacheManager> {
  public:
-  typedef base::Closure PrecacheCompletionCallback;
+  typedef base::Callback<void(bool)> PrecacheCompletionCallback;
 
   PrecacheManager(content::BrowserContext* browser_context,
                   const sync_driver::SyncService* const sync_service);
   ~PrecacheManager() override;
 
   // Returns true if precaching is allowed for the browser context based on user
   // settings, and enabled as part of a field trial or by commandline flag.
   // Virtual for testing.
   virtual bool ShouldRun() const;
 
   // Returns true if precaching is allowed for the browser context based on user
   // settings. Virtual for testing.
   virtual bool WouldRun() const;
 
   // Starts precaching resources that the user is predicted to fetch in the
   // future. If precaching is already currently in progress, then this method
-  // does nothing. The |precache_completion_callback| will be run when
-  // precaching finishes, but will not be run if precaching is canceled.
+  // does nothing. The |precache_completion_callback| will be passed true when
+  // precaching finishes, and passed false when precaching abort due to failed
+  // preconditions, but will not be run if precaching is canceled.
   void StartPrecaching(
       const PrecacheCompletionCallback& precache_completion_callback,
       const history::HistoryService& history_service);
 
   // Cancels precaching if it is in progress.
   void CancelPrecaching();
 
   // Returns true if precaching is currently in progress, or false otherwise.
   bool IsPrecaching() const;
 
@@ skipping 47 matching lines @@
 
   // Flag indicating whether or not precaching is currently in progress.
   bool is_precaching_;
 
   DISALLOW_COPY_AND_ASSIGN(PrecacheManager);
 };
 
 }  // namespace precache
 
 #endif  // COMPONENTS_PRECACHE_CONTENT_PRECACHE_MANAGER_H_