ash:Shelf - Added UMA stats for ShelfAlignment

chrome/browser/metrics/metrics_service.cc

Index: chrome/browser/metrics/metrics_service.cc
diff --git a/chrome/browser/metrics/metrics_service.cc b/chrome/browser/metrics/metrics_service.cc
index d17779b4f2247803aca4d61e06935cb1d4b5ca1a..43bcea1971202534eb3fc2dfbbe2385cd32e02b1 100644
--- a/chrome/browser/metrics/metrics_service.cc
+++ b/chrome/browser/metrics/metrics_service.cc
@@ -152,6 +152,7 @@
 
 #include <algorithm>
 
+#include "ash/launcher/launcher.h"
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/command_line.h"
@@ -1153,6 +1154,13 @@ void MetricsService::SaveLocalState() {
 
   RecordCurrentState(pref);
 
+#if defined(OS_CHROMEOS)
+  // Query the current state of the shelf alignment to gather an impression of
+  // how much user time is being spent in each alignment.
+  ash::Launcher::ForPrimaryDisplay()->RecordCurrentAlignmentForUMAHistogram(

[James Cook, 2013/10/30 16:49:12]

Now that I think about it more, this really needs to be on a repeating task in
Ash.  The metrics service shouldn't be responsible for querying all the modules
that need periodic information to record.  Sorry to give you bad advice before.

See chrome/browser/chromeos/memory/oom_priority_manager.cc
RecordRecentTabDiscard() for how to use a repeating timer for this.

I would introduce some kind of "RecordPeriodicStatistics" function or class in
Ash and stick the code there.  It should have a timer that is explicitly started
and stopped when ash::Shell is initialized and torn down.

+      "Ash.ShelfAlignmentOverTime");
+#endif
+
   // TODO(jar):110021 Does this run down the batteries????
   ScheduleNextStateSave();
 }