Handle interface to prerenders.

chrome/browser/prerender/prerender_manager.h

Index: chrome/browser/prerender/prerender_manager.h
diff --git a/chrome/browser/prerender/prerender_manager.h b/chrome/browser/prerender/prerender_manager.h
index 3fa9591e9629923ea8f0ab379447502f6629ee98..7a8c121125ceafd6deda942fe3d7a44799f0110a 100644
--- a/chrome/browser/prerender/prerender_manager.h
+++ b/chrome/browser/prerender/prerender_manager.h
@@ -12,6 +12,7 @@
 
 #include "base/gtest_prod_util.h"
 #include "base/hash_tables.h"
+#include "base/memory/linked_ptr.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
@@ -55,6 +56,7 @@ struct hash<content::WebContents*> {
 namespace prerender {
 
 class PrerenderCondition;
+class PrerenderHandle;
 class PrerenderHistograms;
 class PrerenderHistory;
 class PrerenderLocalPredictor;
@@ -107,7 +109,7 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
   // Returns true if the URL was added, false if it was not.
   // If the launching RenderView is itself prerendering, the prerender is added
   // as a pending prerender.
-  bool AddPrerenderFromLinkRelPrerender(
+  base::WeakPtr<PrerenderHandle> AddPrerenderFromLinkRelPrerender(
       int process_id,
       int route_id,
       const GURL& url,
@@ -119,14 +121,18 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
   // child or route id, or a referrer. This method uses sensible values for
   // those. The |session_storage_namespace| matches the namespace of the active
   // tab at the time the prerender is generated from the omnibox.
-  bool AddPrerenderFromOmnibox(
+  base::WeakPtr<PrerenderHandle> AddPrerenderFromOmnibox(

[dominich, 2012/06/22 15:36:16]

This cements it for me. I don't like an API that returns a specific smart
pointer and then...

       const GURL& url,
       content::SessionStorageNamespace* session_storage_namespace);
 
-  // Request cancelation of a previously added prerender. If the |active_count_|
-  // of the prerender is one, it will be canceled.  Otherwise, |active_count_|
-  // will be decremented by one.
-  void MaybeCancelPrerender(const GURL& url);
+  // Adds a prerender 
+  void StartPendingPrerender(
+      scoped_ptr<PrerenderHandle> existing_prerender_handle,

[dominich, 2012/06/22 15:36:16]

... uses a different smart pointer to the same type in another part of the
public API.

+      int process_id,
+      const GURL& url,
+      const content::Referrer& referrer,
+      const gfx::Size& size,
+      content::SessionStorageNamespace* session_storage_namespace);

[dominich, 2012/06/22 15:36:16]

ps - why is starting a pending prerender a public operation?

 
   // Destroy all prerenders for the given child route id pair and assign a final
   // status to them.
@@ -137,9 +143,6 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
   // Cancels all active prerenders.
   void CancelAllPrerenders();
 
-  // Cancels all active prerenders with the ORIGIN_OMNIBOX origin.
-  void CancelOmniboxPrerenders();
-
   // If |url| matches a valid prerendered page, try to swap it into
   // |web_contents| and merge browsing histories. Returns |true| if a
   // prerendered page is swapped in, |false| otherwise.
@@ -186,10 +189,6 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
   // is prerendering a page.
   bool IsWebContentsPrerendering(content::WebContents* web_contents) const;
 
-  // Returns true if there is a prerendered page for the given URL and it has
-  // finished loading. Only valid if called before MaybeUsePrerenderedPage.
-  bool DidPrerenderFinishLoading(const GURL& url) const;
-
   // Maintaining and querying the set of WebContents belonging to this
   // PrerenderManager that are currently showing prerendered pages.
   void MarkWebContentsAsPrerendered(content::WebContents* web_contents);
@@ -239,11 +238,6 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
   // Adds a condition. This is owned by the PrerenderManager.
   void AddCondition(const PrerenderCondition* condition);
 
-  bool IsPendingEntry(const GURL& url) const;
-
-  // Returns true if |url| matches any URLs being prerendered.
-  bool IsPrerendering(const GURL& url) const;
-
   // Records that some visible tab navigated (or was redirected) to the
   // provided URL.
   void RecordNavigation(const GURL& url);
@@ -261,6 +255,8 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
   // tests.
   void DoShutdown();
 
+  PrerenderContents* FindEntry(const GURL& url);

[dominich, 2012/06/22 15:36:16]

move to protected for tests?

[gavinp, 2012/06/22 17:45:29]

Yup.

+
  private:
   // Test that needs needs access to internal functions.
   friend class PrerenderBrowserTest;
@@ -299,30 +295,37 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
   FRIEND_TEST_ALL_PREFIXES(PrerenderTest, SourceRenderViewClosed);
   FRIEND_TEST_ALL_PREFIXES(PrerenderTest, TwoElementPrerenderTest);
 
-  struct PrerenderContentsData;
   struct NavigationRecord;
 
   class OnCloseTabContentsDeleter;
 
-  typedef std::list<PrerenderContentsData> PrerenderContentsDataList;
+  typedef std::map<PrerenderContents*, linked_ptr<PrerenderHandle>,
+                   PrerenderContents::LessThanByLoadStartTime>
+      PrerenderHandleMap;

[dominich, 2012/06/22 15:36:16]

if the PrerenderHandle already contains the PrerenderContents* and is the
canonical way to refer to a prerender, why do we need this map going the other
way?

   typedef base::hash_map<content::WebContents*, bool> WouldBePrerenderedMap;
 
   // Time window for which we record old navigations, in milliseconds.
   static const int kNavigationRecordWindowMs = 5000;
 
-  // Adds a prerender for |url| from referrer |referrer| initiated from the
-  // child process specified by |child_id|. The |origin| specifies how the
-  // prerender was added. If the |size| is empty, then
-  // PrerenderContents::StartPrerendering will instead use the size of the
-  // currently active tab. If the current active tab size cannot be found, it
-  // then uses a default from PrerenderConfig.
-  bool AddPrerender(
+  // 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 the
+  // size of the currently active tab. If the current active tab size cannot be
+  // found, it then uses a default from PrerenderConfig. If |prerender_handle|
+  // is NULL, then AddPrerender will allocate a handle for the caller if
+  // successful. If |preexisting_prerender_handle| is not-NULL, the
+  // PrerenderManager will take ownership of it and associate the prerender with
+  // that handle. The return value is a WeakPtr to a PrerenderHandle. It can
+  // be NULL, if for instance Prerendering is disabled or if there was an error
+  // adding this prerender.
+  base::WeakPtr<PrerenderHandle> AddPrerender(
       Origin origin,
       int child_id,
       const GURL& url,
       const content::Referrer& referrer,
       const gfx::Size& size,
-      content::SessionStorageNamespace* session_storage_namespace);
+      content::SessionStorageNamespace* session_storage_namespace,
+      const scoped_ptr<PrerenderHandle> preexisting_prerender_handle);

[dominich, 2012/06/22 15:36:16]

I don't understand why this is passed through and can't be discovered from
within the method.

 
   // Retrieves the PrerenderContents object for the specified URL, if it
   // has been prerendered.  The caller will then have ownership of the
@@ -334,13 +337,14 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
   // The WebContents specified indicates the WC in which to swap the
   // prerendering into.  If the WebContents specified is the one
   // to doing the prerendered itself, will return NULL.
-  PrerenderContents* GetEntryButNotSpecifiedWC(const GURL& url,
-                                               content::WebContents* wc);
+  PrerenderContents* GetEntryButNotSpecifiedWC(
+      const GURL& url,
+      content::WebContents* web_contents);
 
-  // Starts scheduling periodic cleanups.
   void StartSchedulingPeriodicCleanups();
-  // Stops scheduling periodic cleanups if they're no longer needed.
-  void MaybeStopSchedulingPeriodicCleanups();
+  void StopSchedulingPeriodicCleanups();
+
+  void EvictOldestPrerendersIfNecessary();
 
   // Deletes stale and cancelled prerendered PrerenderContents, as well as
   // WebContents that have been replaced by prerendered WebContents.
@@ -354,7 +358,7 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
   void PostCleanupTask();
 
   base::TimeDelta GetMaxAge() const;
-  bool IsPrerenderElementFresh(const base::Time start) const;
+  bool IsPrerenderFresh(base::TimeTicks start) const;
   void DeleteOldEntries();
   virtual base::Time GetCurrentTime() const;
   virtual base::TimeTicks GetCurrentTimeTicks() const;
@@ -368,20 +372,13 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
   // list.
   void DeletePendingDeleteEntries();
 
-  // Finds the specified PrerenderContentsData/PrerenderContents and returns it,
-  // if it exists. Returns NULL otherwise.  Unlike GetEntry, the
   // PrerenderManager maintains ownership of the PrerenderContents.
-  PrerenderContentsData* FindEntryData(const GURL& url);
-  PrerenderContents* FindEntry(const GURL& url) const;
-
-  // Returns the iterator to the PrerenderContentsData entry that is being
-  // prerendered from the given child route id pair.
-  PrerenderContentsDataList::iterator
-      FindPrerenderContentsForChildRouteIdPair(
-          const std::pair<int, int>& child_route_id_pair);
+  PrerenderHandle* FindHandle(

[dominich, 2012/06/22 15:36:16]

with all those smart pointer returns, i'm surprised that this is returning a raw
pointer.

+      const GURL& url,
+      const content::SessionStorageNamespace* session_storage_namespace);
 
-  PrerenderContentsDataList::iterator
-      FindPrerenderContentsForURL(const GURL& url);
+  // PrerenderManager maintains ownership of the PrerenderContents.
+  PrerenderContents* FindContentsForChildAndRoute(int child_id, int route_id);

[dominich, 2012/06/22 15:36:16]

If we add a new prerender for the same URL/SessionStorage but from a different
child_id/route_id, is that a new PrerenderHandle or is it a new client of an
existing one?

 
   bool DoesRateLimitAllowPrerender() const;
 
@@ -442,8 +439,9 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
 
   PrerenderTracker* prerender_tracker_;
 
-  // List of prerendered elements.
-  PrerenderContentsDataList prerender_list_;
+  // Map of prerendered elements. This map owns both each PrerenderHandle* and
+  // each PrerenderContents* in it.
+  PrerenderHandleMap prerender_map_;
 
   // List of recent navigations in this profile, sorted by ascending
   // navigate_time_.