Updating histograms to allow for experiments & log origin-based histograms.

chrome/browser/prerender/prerender_manager.h

Index: chrome/browser/prerender/prerender_manager.h
===================================================================
--- chrome/browser/prerender/prerender_manager.h	(revision 91002)
+++ chrome/browser/prerender/prerender_manager.h	(working copy)
@@ -67,6 +67,9 @@
     CLEAR_MAX = 0x1 << 2
   };
 
+  // ID indicating that no experiment is active.
+  static const uint8 kNoExperiment = 0;
+
   // Owned by a Profile object for the lifetime of the profile.
   PrerenderManager(Profile* profile, PrerenderTracker* prerender_tracker);
 
@@ -185,6 +188,11 @@
   // Intended to be used when clearing the cache or history.
   void ClearData(int clear_flags);
 
+  // Record a final status of a prerendered page in a histogram.
+  void RecordFinalStatus(Origin origin,
+                         uint8 experiment_id,
+                         FinalStatus final_status) const;
+
  protected:
   // Test that needs needs access to internal functions.
   FRIEND_TEST_ALL_PREFIXES(PrerenderManagerTest, ExpireTest);
@@ -199,12 +207,6 @@
 
   PendingContentsData* FindPendingEntry(const GURL& url);
 
-  // Extracts a urlencoded URL stored in a url= query parameter from a URL
-  // supplied, if available, and stores it in alias_url.  Returns whether or not
-  // the operation succeeded (i.e. a valid URL was found).
-  static bool MaybeGetQueryStringBasedAliasURL(const GURL& url,
-                                               GURL* alias_url);
-
   base::TimeDelta max_prerender_age() const;
   unsigned int max_elements() const;
 
@@ -258,7 +260,8 @@
   virtual base::TimeTicks GetCurrentTimeTicks() const;
   virtual PrerenderContents* CreatePrerenderContents(const GURL& url,
                                                      const GURL& referrer,
-                                                     Origin origin);
+                                                     Origin origin,
+                                                     uint8 experiment_id);
 
   // Checks if the PrerenderContents has been added to the pending delete list.
   bool IsPendingDelete(PrerenderContents* entry) const;
@@ -322,6 +325,22 @@
   // navigates to it. This must be called on the UI thread.
   void RecordTimeUntilUsed(base::TimeDelta time_until_used);
 
+  // Composes a histogram name based on a histogram type.

[dominich, 2011/06/30 21:44:59]

Do these need to be in PrerenderManager? It seems they should be in a
prerender_histogram file in the top-level prerender namespace, or at least in a
class to track the last experiment/wash stuff.

+  std::string ComposeHistogramName(const std::string& prefix_type,
+                                   const std::string& name) const;
+
+  // Returns the histogram name for a given origin and experiment.
+  std::string GetHistogramName(Origin origin, uint8 experiment_id,
+                               const std::string& name) const;
+  // Returns the histogram name for the current window.
+  std::string GetDefaultHistogramName(const std::string& name) const;
+  // Returns the current experiment.
+  uint8 GetCurrentExperimentId() const;
+  // Returns the current origin.
+  Origin GetCurrentOrigin() const;
+  // Returns whether or not there is currently an origin/experiment wash.
+  bool IsOriginExperimentWash() const;
+
   // Specifies whether prerendering is currently enabled for this
   // manager. The value can change dynamically during the lifetime
   // of the PrerenderManager.
@@ -363,6 +382,18 @@
 
   static PrerenderManagerMode mode_;
 
+  // An integer indicating a Prerendering Experiment being currently conducted.
+  // (The last experiment ID seen).
+  uint8 last_experiment_id_;
+
+  // Origin of the last prerender seen.
+  Origin last_origin_;
+
+  // A boolean indicating that we have recently encountered a combination of
+  // different experiments and origins, making an attribution of PPLT's to
+  // experiments / origins impossible.
+  bool origin_experiment_wash_;
+
   // The time when we last saw a prerender request coming from a renderer.
   // This is used to record perceived PLT's for a certain amount of time
   // from the point that we last saw a <link rel=prerender> tag.