Make three simultanious prerenders the default maximum in Canary and Dev only.

chrome/browser/prerender/prerender_manager.h

 // Copyright (c) 2012 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_PRERENDER_PRERENDER_MANAGER_H_
 #define CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_H_
 
 #include <list>
 #include <map>
 #include <string>
@@ skipping 56 matching lines @@
 // indicated otherwise.
 class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
                          public base::NonThreadSafe,
                          public ProfileKeyedService {
  public:
   // PrerenderManagerMode is used in a UMA_HISTOGRAM, so please do not
   // add in the middle.
   enum PrerenderManagerMode {
     PRERENDER_MODE_DISABLED,
     PRERENDER_MODE_ENABLED,
+    PRERENDER_MODE_EXPERIMENT_PRERENDER_GROUP,
     PRERENDER_MODE_EXPERIMENT_CONTROL_GROUP,
-    PRERENDER_MODE_EXPERIMENT_PRERENDER_GROUP,
+    PRERENDER_MODE_EXPERIMENT_MULTI_PRERENDER_GROUP,
     PRERENDER_MODE_EXPERIMENT_5MIN_TTL_GROUP,
     PRERENDER_MODE_EXPERIMENT_NO_USE_GROUP,
     PRERENDER_MODE_MAX
   };
 
   // One or more of these flags must be passed to ClearData() to specify just
   // what data to clear.  See function declaration for more information.
   enum ClearFlags {
     CLEAR_PRERENDER_CONTENTS = 0x1 << 0,
     CLEAR_PRERENDER_HISTORY = 0x1 << 1,
@@ skipping 80 matching lines @@
   static bool IsPrefetchEnabled();
   static void SetIsPrefetchEnabled(bool enabled);
 
   static PrerenderManagerMode GetMode();
   static void SetMode(PrerenderManagerMode mode);
   static const char* GetModeString();
   static bool IsPrerenderingPossible();
   static bool ActuallyPrerendering();
   static bool IsControlGroup();
   static bool IsNoUseGroup();
+  static size_t GetMaxConcurrency();
 
   // Query the list of current prerender pages to see if the given web contents
   // is prerendering a page.
   bool IsWebContentsPrerendering(content::WebContents* web_contents) const;
 
   // Maintaining and querying the set of WebContents belonging to this
   // PrerenderManager that are currently showing prerendered pages.
   void MarkWebContentsAsPrerendered(content::WebContents* web_contents);
   void MarkWebContentsAsWouldBePrerendered(content::WebContents* web_contents);
   void MarkWebContentsAsNotPrerendered(content::WebContents* web_contents);
@@ skipping 117 matching lines @@
   friend class PrerenderBrowserTest;
   friend class PrerenderContents;
   friend class PrerenderHandle;
   friend class UnitTestPrerenderManager;
 
   class OnCloseTabContentsDeleter;
   struct NavigationRecord;
 
   typedef base::hash_map<content::WebContents*, bool> WouldBePrerenderedMap;
 
+  // Time interval before a new prerender is allowed.
+  static const int kMinTimeBetweenPrerendersMs = 500;
+
   // Time window for which we record old navigations, in milliseconds.
   static const int kNavigationRecordWindowMs = 5000;
 
   void OnCancelPrerenderHandle(PrerenderData* prerender_data);
 
   // Adds a prerender for |url| from |referrer| initiated from the process
   // |child_id|. The |origin| specifies how the prerender was added. If |size|
   // is empty, then PrerenderContents::StartPrerendering will instead use a
   // default from PrerenderConfig. Returns a PrerenderHandle*, owned by the
   // caller, or NULL.
@@ skipping 171 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(PrerenderManager);
 };
 
 PrerenderManager* FindPrerenderManagerUsingRenderProcessId(
     int render_process_id);
 
 }  // namespace prerender
 
 #endif  // CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_H_