Correctly record TouchView metrics on suspend/shutdown

ash/wm/maximize_mode/maximize_mode_controller.h

Index: ash/wm/maximize_mode/maximize_mode_controller.h
diff --git a/ash/wm/maximize_mode/maximize_mode_controller.h b/ash/wm/maximize_mode/maximize_mode_controller.h
index f7959661cfb9f6468382b6f267da677b58196f87..491a77e6aaab969748126cd1d97b1757be3af240 100644
--- a/ash/wm/maximize_mode/maximize_mode_controller.h
+++ b/ash/wm/maximize_mode/maximize_mode_controller.h
@@ -97,6 +97,13 @@ class ASH_EXPORT MaximizeModeController :
   friend class test::MultiUserWindowManagerChromeOSTest;
   friend class test::VirtualKeyboardControllerTest;
 
+  // Used for recording metrics for intervals of time spent in
+  // and out of TouchView.
+  enum TouchViewIntervalType {

[flackr, 2015/02/12 19:59:06]

Why not a bool if we only have active an inactive? I.e. bool touchview_active
param on the record usage method?

[tdanderson, 2015/02/12 20:30:49]

I prefer enums over bools in cases where it would improve readability at call
sites. RecordTouchViewUsageInterval(TOUCH_VIEW_INTERVAL_ACTIVE) is more
self-documenting than RecordTouchViewUsageInterval(true). But if you prefer that
I use a bool instead, I'm ok with that too.

[flackr, 2015/02/12 20:44:43]

Can also use RecordTouchViewUsageInterval(/* touchview_active */ true) which is
fairly prevalent in codebase:
https://code.google.com/p/chromium/codesearch#search/&q=%5C/%5C*%5C%20%5B%5E*...
of course not strictly enforced. I don't have a strong preference though.

[jonross, 2015/02/12 20:49:26]

using a bool would clean up some of the logic in the *.cc file.

[tdanderson, 2015/02/12 21:38:22]

Rob and I had a chat offline and he's OK leaving this as an enum.

+    TOUCH_VIEW_INTERVAL_INACTIVE,
+    TOUCH_VIEW_INTERVAL_ACTIVE
+  };
+
   // Set the TickClock. This is only to be used by tests that need to
   // artificially and deterministically control the current time.
   void SetTickClockForTest(scoped_ptr<base::TickClock> tick_clock);
@@ -118,8 +125,12 @@ class ASH_EXPORT MaximizeModeController :
   // is no rotation lock.
   void LeaveMaximizeMode();
 
-  // Record UMA stats tracking touchview usage.
-  void RecordTouchViewStateTransition();
+  // Record UMA stats tracking TouchView usage. If |type| is
+  // TOUCH_VIEW_INTERVAL_INACTIVE, then record that TouchView has been
+  // inactive from |touchview_usage_interval_start_time_| until now.
+  // Similarly, record that TouchView has been active if |type| is
+  // TOUCH_VIEW_INTERVAL_ACTIVE.
+  void RecordTouchViewUsageInterval(TouchViewIntervalType type);
 
   // The maximized window manager (if enabled).
   scoped_ptr<MaximizeModeWindowManager> maximize_mode_window_manager_;
@@ -135,7 +146,7 @@ class ASH_EXPORT MaximizeModeController :
   bool lid_open_past_180_;
 
   // Tracks time spent in (and out of) touchview mode.
-  base::Time last_touchview_transition_time_;
+  base::Time touchview_usage_interval_start_time_;
   base::TimeDelta total_touchview_time_;
   base::TimeDelta total_non_touchview_time_;