Don't report a keepalive count for persistent pages.

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 <stdint.h>
 
 #include <map>
@@ skipping 99 matching lines @@
   // WebContents, or null.
   const Extension* GetExtensionForRenderFrameHost(
       content::RenderFrameHost* render_frame_host);
   const Extension* GetExtensionForWebContents(
       const content::WebContents* web_contents);
 
   // Getter and setter for the lazy background page's keepalive count. This is
   // the count of how many outstanding "things" are keeping the page alive.
   // When this reaches 0, we will begin the process of shutting down the page.
   // "Things" include pending events, resource loads, and API calls.
+  // Returns -1 if |extension| has a persistent background page.

[Devlin, 2017/02/14 16:18:24]

nit: s/has a persistent background page/doesn't have a lazy background page.

[Wez, 2017/02/14 17:39:16]

Done.

   int GetLazyKeepaliveCount(const Extension* extension);
   void IncrementLazyKeepaliveCount(const Extension* extension);
   void DecrementLazyKeepaliveCount(const Extension* extension);
 
   // Keeps a background page alive. Unlike IncrementLazyKeepaliveCount, these
   // impulses will only keep the page alive for a limited amount of time unless
   // called regularly.
   void KeepaliveImpulse(const Extension* extension);
 
   // Triggers a keepalive impulse for a plugin (e.g NaCl).
@@ skipping 207 matching lines @@
 
   // Must be last member, see doc on WeakPtrFactory.
   base::WeakPtrFactory<ProcessManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ProcessManager);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_PROCESS_MANAGER_H_