[chromecast] ExternalMetrics has to destroy itself in file thread.

chromecast/browser/metrics/external_metrics.h

Index: chromecast/browser/metrics/external_metrics.h
diff --git a/chromecast/browser/metrics/external_metrics.h b/chromecast/browser/metrics/external_metrics.h
index 47c74f3eebe26181148211fa67e87f84d529dee1..586554b8509ba4179146688ca7db9e4311ef6422 100644
--- a/chromecast/browser/metrics/external_metrics.h
+++ b/chromecast/browser/metrics/external_metrics.h
@@ -30,6 +30,9 @@ class ExternalMetrics {
   // File thread but are executed in the UI thread.
   void Start();
 
+  // Destroy itself in appropriate thread.

[gunsch, 2015/01/09 18:56:19]

nit: "Destroy" --> "Destroys"

[gfhuang, 2015/01/09 19:10:46]

Done.

+  void DestroySelf();
+
  private:
   // The max length of a message (name-value pair, plus header)
   static const int kMetricsMessageMaxLength = 1024;  // be generous