ThreadWatcher - On Android, don't generate the crash dump if

chrome/browser/metrics/thread_watcher.cc

Index: chrome/browser/metrics/thread_watcher.cc
diff --git a/chrome/browser/metrics/thread_watcher.cc b/chrome/browser/metrics/thread_watcher.cc
index ab80a8680dae484a3edb303576b5a17b35f8c631..3ec771143ac150b6f31cf89e80eb3e9d3e0bcfcb 100644
--- a/chrome/browser/metrics/thread_watcher.cc
+++ b/chrome/browser/metrics/thread_watcher.cc
@@ -53,6 +53,13 @@ void NullPointerCrash(int line_number) {
 #endif
 }
 
+#if !defined(OS_ANDROID)
+// TODO(rtenneti): Enabled crashing, after getting data.
+NOINLINE void StartupCrash() {
+  NullPointerCrash(__LINE__);
+}
+#endif  // OS_ANDROID
+
 NOINLINE void ShutdownCrash() {
   NullPointerCrash(__LINE__);
 }
@@ -882,20 +889,48 @@ 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
   // Disarm(). When Alarm goes off, in release mode we get the crash dump
   // without crashing and in debug mode we break into the debugger.
   virtual void Alarm() OVERRIDE {
+#if defined(OS_ANDROID)
+    // TODO(rtenneti): Delete this code, after getting data.
+    // On Android, we don't crash, but we will collect stats.
+    UMA_HISTOGRAM_TIMES("StartupTimebomm.Alarm.TimeDuration",
+                        base::Time::Now() - start_time_clock_);
+    UMA_HISTOGRAM_TIMES("StartupTimebomm.Alarm.TimeTicksDuration",
+                        base::TimeTicks::Now() - start_time_monotonic_);
+    if (base::TimeTicks::IsThreadNowSupported()) {
+      UMA_HISTOGRAM_TIMES(
+          "StartupTimebomm.Alarm.ThreadNowDuration",
+          base::TimeTicks::ThreadNow() - start_time_thread_now_);
+    }
+#else
 #ifndef NDEBUG

[jar (doing other things), 2014/05/03 02:00:21]

nit: I like less ifdef protected, and especially nested, blocks.  One small
change that might help is to change:

#else
#ifndef NDEBUG

into

#elif !defined(NDEBUG)


Maybe even nicer would be list the three block, each with a return, and to list
the smallest blocks first (for easy reading).  Something like

#if !defined(NDEBUG)
  DCHECK(false);
  return;
#elif !defined(OS_ANDROID)
  PostTask(to crash);
  return;
#else  // Android release: gather stats to figure out when to crash.
  UMA_HISTOGRAMS(...)
  return;
#endif

[ramant (doing other things), 2014/05/03 04:11:36]

Done.

-    DCHECK(false);
+    StartupCrash();
 #else
-    WatchDogThread::PostTask(FROM_HERE,
-                             base::Bind(&base::debug::DumpWithoutCrashing));

[jar (doing other things), 2014/05/03 02:00:21]

Is this a deliberate change to crashing?  Did you turn off crashing... and now
this will turn it back on for non-Android?

[ramant (doing other things), 2014/05/03 04:11:36]

In DEBUG builds we used to crash and we do the same.

For non DEBUG builds, instead of calling DumpWithoutCrashing directly, called
StartupCrash which calls DumpWithoutCrashing. This would show StartupCrash in
callstack (it would help in isolating if there are other watchdog based
crashes).

void NullPointerCrash(int line_number) {
#ifndef NDEBUG
  *NullPointer() = line_number;  // Crash.
#else
  base::debug::DumpWithoutCrashing();
#endif
}

NOINLINE void StartupCrash() {
  NullPointerCrash(__LINE__);
}

WDYT?

-#endif
+    WatchDogThread::PostTask(FROM_HERE, base::Bind(&StartupCrash));
+#endif  // NDEBUG
+#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);
 };
 
@@ -916,6 +951,7 @@ class ShutdownWatchDogThread : public base::Watchdog {
     ShutdownCrash();
   }
 
+ private:
   DISALLOW_COPY_AND_ASSIGN(ShutdownWatchDogThread);
 };
 }  // namespace