Tweaks to the precache triggering code.

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 42 matching lines @@
 class PrecacheManager : public KeyedService,
                         public PrecacheFetcher::PrecacheDelegate,
                         public base::SupportsWeakPtr<PrecacheManager> {
  public:
   typedef base::Closure PrecacheCompletionCallback;
 
   PrecacheManager(content::BrowserContext* browser_context,
                   const sync_driver::SyncService* const sync_service);
   ~PrecacheManager() override;
 
-  // Returns true if precaching is enabled as part of a field trial or by the
-  // command line flag. This method can be called on any thread.
-  static bool IsPrecachingEnabled();
+  // 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;

[bengr, 2015/08/07 17:21:45]

I'm not a huge fan of these names, but am ok with the change.

[twifkak, 2015/08/07 17:57:08]

I'm not a huge fan of them either. When I introduce the control group, I'm
thinking of renaming them to InExperimentGroup and InControlGroup. (Sorry for
the naming churn. I can't do it on this CL because "control group" is a bit of a
misnomer - gives the wrong impression that it only happens for a field trial
group.)

 
-  // Returns true if precaching is allowed for the browser context.
-  bool IsPrecachingAllowed();
+  // 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.
   void StartPrecaching(
       const PrecacheCompletionCallback& precache_completion_callback,
       const history::HistoryService& history_service);
 
   // Cancels precaching if it is in progress.
@@ skipping 15 matching lines @@
  private:
   // From KeyedService.
   void Shutdown() override;
 
   // From PrecacheFetcher::PrecacheDelegate.
   void OnDone() override;
 
   // From history::HistoryService::TopHosts.
   void OnHostsReceived(const history::TopHostsList& host_counts);
 
+  // Returns true if precaching is enabled as part of a field trial or by the
+  // command line flag. This has a different meaning from the
+  // "is_precaching_enabled" pref set in PrecacheServiceLauncher. This method
+  // can be called on any thread.
+  static bool IsPrecachingEnabled();
+
+  // Returns true if precaching is allowed for the browser context.
+  bool IsPrecachingAllowed() const;
+
   // The browser context that owns this PrecacheManager.
   content::BrowserContext* const browser_context_;
 
   // The sync service corresponding to the browser context. Used to determine
   // whether precache can run. May be null.
   const sync_driver::SyncService* const sync_service_;
 
   // The PrecacheFetcher used to precache resources. Should only be used on the
   // UI thread.
   scoped_ptr<PrecacheFetcher> precache_fetcher_;
 
   // The callback that will be run if precaching finishes without being
   // canceled.
   PrecacheCompletionCallback precache_completion_callback_;
 
   // The PrecacheDatabase for tracking precache metrics. Should only be used on
   // the DB thread.
   const scoped_refptr<PrecacheDatabase> precache_database_;
 
   // 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_