Add histogram coverage of session service Save() operations, namely the time between successive Save() operations.

BUG=none
TEST=about:histograms

Review URL: http://codereview.chromium.org/2732005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@49420 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 12 insertions, 1 deletions

diff --git a/chrome/browser/sessions/session_service.h b/chrome/browser/sessions/session_service.h
index 0611842..cfb3a8d 100644
--- a/chrome/browser/sessions/session_service.h
+++ b/chrome/browser/sessions/session_service.h
@@ -9,6 +9,7 @@
 
 #include "base/basictypes.h"
 #include "base/callback.h"
+#include "base/time.h"
 #include "chrome/browser/browser.h"
 #include "chrome/browser/browser_list.h"
 #include "chrome/browser/defaults.h"
@@ -169,6 +170,10 @@ class SessionService : public BaseSessionService,
   Handle GetCurrentSession(CancelableRequestConsumerBase* consumer,
                            SessionCallback* callback);
 
+  // Overridden from BaseSessionService because we want some UMA reporting on
+  // session update activities.
+  virtual void Save();
+
  private:
   typedef std::map<SessionID::id_type,std::pair<int,int> > IdToRange;
   typedef std::map<SessionID::id_type,SessionTab*> IdToSessionTab;
@@ -374,7 +379,10 @@ class SessionService : public BaseSessionService,
     return !has_open_trackable_browsers_ &&
         (!browser_defaults::kBrowserAliveWithNoWindows ||
          BrowserList::size() > 1);
-    }
+  }
+
+  // Call when a Save() occurs to record this in UMA stats.
+  void RecordSaveHistogramData();
 
   // Convert back/forward between the Browser and SessionService DB window
   // types.
@@ -421,6 +429,9 @@ class SessionService : public BaseSessionService,
   // current/previous session.
   bool move_on_new_browser_;
 
+  // Used for reporting frequency of Save() operations.
+  base::TimeTicks last_save_time_;
+
   DISALLOW_COPY_AND_ASSIGN(SessionService);
 };