Allow the minimum time between banner trigger visits to be varied via field trials.

chrome/browser/banners/app_banner_manager.h

 // Copyright 2015 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 CHROME_BROWSER_BANNERS_APP_BANNER_MANAGER_H_
 #define CHROME_BROWSER_BANNERS_APP_BANNER_MANAGER_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 64 matching lines @@
   // Called after the manager sends a message to the renderer regarding its
   // intention to show a prompt. The renderer will send a message back with the
   // opportunity to cancel.
   void OnBannerPromptReply(content::RenderFrameHost* render_frame_host,
                            int request_id,
                            blink::WebAppBannerPromptReply reply);
 
   // Cancels an active DataFetcher, stopping its banners from appearing.
   void CancelActiveFetcher();
 
+  // Queries a field trial for updates to the default number of minutes between
+  // site visits counted for the purposes of displaying a banner.
+  void UpdateMinutesBetweenVisits();
+
   // Ideal icon size to use.
   const int ideal_icon_size_;
 
   // The type of navigation made to the page
   ui::PageTransition last_transition_type_;
 
   // Fetches the data required to display a banner for the current page.
   scoped_refptr<AppBannerDataFetcher> data_fetcher_;
 
   // A weak pointer is used as the lifetime of the ServiceWorkerContext is
   // longer than the lifetime of this banner manager. The banner manager
   // might be gone when calls sent to the ServiceWorkerContext are completed.
   base::WeakPtrFactory<AppBannerManager> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AppBannerManager);
 };  // class AppBannerManager
 
 }  // namespace banners
 
 #endif  // CHROME_BROWSER_BANNERS_APP_BANNER_MANAGER_H_