Fix prerender histograms for multiple prerender case.

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 0245b2c992cc9b40150bcb0308cae751941c5fc2..ede15169c0c740abcbd0450d7b18a605183dc69d 100644
--- a/chrome/browser/prerender/prerender_manager.h
+++ b/chrome/browser/prerender/prerender_manager.h
@@ -159,6 +159,11 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
       content::WebContents* web_contents,
       const GURL& url);
 
+  // Records the percentage of pixels of the final page in place at swap-in.
+  void RecordFractionPixelsFinalAtSwapin(
+      content::WebContents* web_contents,
+      double fraction);
+
   // Set whether prerendering is currently enabled for this manager.
   // Must be called on the UI thread.
   // If |enabled| is false, existing prerendered pages will still persist until
@@ -189,14 +194,22 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
 
   // Maintaining and querying the set of WebContents belonging to this
   // PrerenderManager that are currently showing prerendered pages.
-  void MarkWebContentsAsPrerendered(content::WebContents* web_contents);
+  void MarkWebContentsAsPrerendered(content::WebContents* web_contents,
+                                    Origin origin);
+
   void MarkWebContentsAsWouldBePrerendered(content::WebContents* web_contents);
   void MarkWebContentsAsNotPrerendered(content::WebContents* web_contents);
-  bool IsWebContentsPrerendered(content::WebContents* web_contents) const;
+
+  // Returns true if |web_contents| is being prerendered. The optional parameter
+  // |origin| is an output parameter which if passed non-null is set to point
+  // to the Origin of that prerender if one is found, NULL otherwise.
+  bool IsWebContentsPrerendered(content::WebContents* web_contents,
+                                const Origin** origin) const;
+
   bool WouldWebContentsBePrerendered(content::WebContents* web_contents) const;
 
   // Checks whether |url| has been recently navigated to.
-  bool HasRecentlyBeenNavigatedTo(const GURL& url);
+  bool HasRecentlyBeenNavigatedTo(Origin origin, const GURL& url);
 
   // Returns true if the method given is invalid for prerendering.
   static bool IsValidHttpMethod(const std::string& method);
@@ -242,7 +255,7 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
 
   Profile* profile() const { return profile_; }
 
-  PrerenderHistograms* histograms() const { return histograms_.get(); }
+  PrerenderHistograms* histograms() { return histograms_.get(); }
 
  protected:
   class PrerenderData : public base::SupportsWeakPtr<PrerenderData> {
@@ -334,6 +347,11 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
 
   class OnCloseTabContentsDeleter;
   struct NavigationRecord;
+  struct PrerenderedWebContentsData {
+    Origin origin;
+
+    explicit PrerenderedWebContentsData(Origin origin);
+  };
 
   typedef base::hash_map<content::WebContents*, bool> WouldBePrerenderedMap;
 
@@ -411,7 +429,7 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
   std::list<linked_ptr<PrerenderData> >::iterator
       FindIteratorForPrerenderContents(PrerenderContents* prerender_contents);
 
-  bool DoesRateLimitAllowPrerender() const;
+  bool DoesRateLimitAllowPrerender(Origin origin) const;
 
   // Deletes old WebContents that have been replaced by prerendered ones.  This
   // is needed because they're replaced in a callback from the old WebContents,
@@ -485,7 +503,8 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
   std::list<PrerenderContents*> pending_delete_list_;
 
   // Set of WebContents which are currently displaying a prerendered page.

[mmenke, 2012/10/05 17:01:15]

While you're here, could you clarify this comment?  "displaying" means
WebContents that have been swapped into a tab.

WebContents currently being prerendered are not in the set.

[gavinp, 2012/10/05 20:43:35]

Done.

-  base::hash_set<content::WebContents*> prerendered_tab_contents_set_;
+  base::hash_map<content::WebContents*, PrerenderedWebContentsData>
+      prerendered_web_contents_data_;
 
   // WebContents that would have been swapped out for a prerendered WebContents
   // if the user was not part of the control group for measurement. When the