ThreadWacther - delete the code for Android that collected stats for

StartupTimeBombAlarm.

Added a TODO to enable StartupTimeBomb for Android.

Reverting the following two CL's manaually:

https://codereview.chromium.org/269763002
https://codereview.chromium.org/273963002

R=jar@chromium.org
BUG=366699

Review URL: https://codereview.chromium.org/672973002

Cr-Commit-Position: refs/heads/master@{#300972}

chrome/browser/metrics/thread_watcher.cc

@@ -920,13 +920,6 @@ class StartupWatchDogThread : public base::Watchdog {
   // alarming.
   explicit StartupWatchDogThread(const base::TimeDelta& duration)
       : base::Watchdog(duration, "Startup watchdog thread", true) {
-#if defined(OS_ANDROID)
-    // TODO(rtenneti): Delete this code, after getting data.
-    start_time_clock_= base::Time::Now();
-    start_time_monotonic_ = base::TimeTicks::Now();
-    start_time_thread_now_ = base::TimeTicks::IsThreadNowSupported()
-        ? base::TimeTicks::ThreadNow() : base::TimeTicks::Now();
-#endif  // OS_ANDROID
   }
 
   // Alarm is called if the time expires after an Arm() without someone calling
@@ -939,29 +932,12 @@ class StartupWatchDogThread : public base::Watchdog {
 #elif !defined(OS_ANDROID)
     WatchDogThread::PostTask(FROM_HERE, base::Bind(&StartupHang));
     return;
-#else  // Android release: gather stats to figure out when to crash.
-    // TODO(rtenneti): Delete this code, after getting data.
-    UMA_HISTOGRAM_TIMES("StartupTimeBomb.Alarm.TimeDuration",
-                        base::Time::Now() - start_time_clock_);
-    UMA_HISTOGRAM_TIMES("StartupTimeBomb.Alarm.TimeTicksDuration",
-                        base::TimeTicks::Now() - start_time_monotonic_);
-    if (base::TimeTicks::IsThreadNowSupported()) {
-      UMA_HISTOGRAM_TIMES(
-          "StartupTimeBomb.Alarm.ThreadNowDuration",
-          base::TimeTicks::ThreadNow() - start_time_thread_now_);
-    }
-    return;
+#else
+    // TODO(rtenneti): Enable crashing for Android.
 #endif  // OS_ANDROID
   }
 
  private:
-#if defined(OS_ANDROID)
-  // TODO(rtenneti): Delete this code, after getting data.
-  base::Time start_time_clock_;
-  base::TimeTicks start_time_monotonic_;
-  base::TimeTicks start_time_thread_now_;
-#endif  // OS_ANDROID
-
   DISALLOW_COPY_AND_ASSIGN(StartupWatchDogThread);
 };
 

tools/metrics/histograms/histograms.xml

@@ -34098,6 +34098,9 @@ Therefore, the affected-histogram name has to have at least one dot in it.
 
 <histogram name="StartupTimeBomb.Alarm" units="milliseconds">
   <owner>rtenneti@chromium.org</owner>
+  <obsolete>
+    Deprecated as of 10/2014.
+  </obsolete>
   <summary>
     Time duration measured from the time the startup timebomb was started and
     when it went off.
@@ -57605,6 +57608,9 @@ To add a new entry, add it with any value and run test to compute valid value.
 </histogram_suffixes>
 
 <histogram_suffixes name="StartupTimeBombAlarm" separator=".">
+  <obsolete>
+    Deprecated as of 10/2014.
+  </obsolete>
   <suffix name="ThreadNowDuration" label="Duration is in thread CPU time."/>
   <suffix name="TimeDuration" label="Duration is in clock time."/>
   <suffix name="TimeTicksDuration" label="Duration is in TimeTicks time."/>