Update last audio tick time during suspend and resume.

media/audio/audio_manager.cc

Index: media/audio/audio_manager.cc
diff --git a/media/audio/audio_manager.cc b/media/audio/audio_manager.cc
index 70e09512af0962d6604b4700ecc80aa2307e5dfc..75e9a53819d5bca6189f46ec2ebcb9052cb44131 100644
--- a/media/audio/audio_manager.cc
+++ b/media/audio/audio_manager.cc
@@ -9,6 +9,7 @@
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
+#include "base/power_monitor/power_monitor.h"
 #include "build/build_config.h"
 #include "media/audio/fake_audio_log_factory.h"
 
@@ -19,19 +20,29 @@ AudioManager* g_last_created = NULL;
 // Helper class for managing global AudioManager data and hang timers. If the
 // audio thread is unresponsive for more than a minute we want to crash the
 // process so we can catch offenders quickly in the field.
-class AudioManagerHelper {
+class AudioManagerHelper : public base::PowerObserver {
  public:
   AudioManagerHelper() : max_hung_task_time_(base::TimeDelta::FromMinutes(1)) {}
-  ~AudioManagerHelper() {}
+  ~AudioManagerHelper() override {}
 
   void StartHangTimer(
       const scoped_refptr<base::SingleThreadTaskRunner>& monitor_task_runner) {
     CHECK(!monitor_task_runner_);
     monitor_task_runner_ = monitor_task_runner;
+    base::PowerMonitor::Get()->AddObserver(this);
     UpdateLastAudioThreadTimeTick();
     CrashOnAudioThreadHang();
   }
 
+  void OnSuspend() override {
+    base::AutoLock lock(hang_lock_);
+    last_audio_thread_timer_tick_ = base::TimeTicks::Now();
+  }
+
+  void OnResume() override {

[nasko, 2015/03/26 23:10:43]

Are we guaranteed that there will be no task execution between resuming and this
call? I wonder if this notification is done after executing some existing tasks
on the message loop, because that has the potential to cause the delayed crash
task to execute before the resume handler has run. Maybe add a guard boolean
that we set on suspend and reset on resume? 

[DaleCurtis, 2015/03/26 23:26:45]

Ah, I was going to do this, but thought it wasn't any better than what I have
now, but thinking about it more, you're right, it's better. Done!

+    OnSuspend();

[nasko, 2015/03/26 23:10:44]

nit: Why not add a private method that does the work and call it from both
observer methods? Calling OnSuspend handler when resuming is ... awkward.

[DaleCurtis, 2015/03/26 23:26:45]

No need anymore.

+  }
+
   // Runs on |monitor_task_runner| typically, but may be started on any thread.
   void CrashOnAudioThreadHang() {
     base::AutoLock lock(hang_lock_);