Add window states docked; and docked minimized. Add wm window event to set docked and undocked.

ash/metrics/user_metrics_recorder.cc

Index: ash/metrics/user_metrics_recorder.cc
diff --git a/ash/metrics/user_metrics_recorder.cc b/ash/metrics/user_metrics_recorder.cc
index 98f0b7f0ad8f445f33b7ca0b47e28623194b2a32..e39f4c6627c1145e9342f28739c5652cc0686461 100644
--- a/ash/metrics/user_metrics_recorder.cc
+++ b/ash/metrics/user_metrics_recorder.cc
@@ -398,6 +398,7 @@ void UserMetricsRecorder::RecordPeriodicMetrics() {
     ACTIVE_WINDOW_STATE_TYPE_MAXIMIZED,
     ACTIVE_WINDOW_STATE_TYPE_FULLSCREEN,
     ACTIVE_WINDOW_STATE_TYPE_SNAPPED,
+    ACTIVE_WINDOW_STATE_TYPE_DOCKED,
     ACTIVE_WINDOW_STATE_TYPE_COUNT
   };
 
@@ -416,6 +417,10 @@ void UserMetricsRecorder::RecordPeriodicMetrics() {
       case wm::WINDOW_STATE_TYPE_RIGHT_SNAPPED:
         active_window_state_type = ACTIVE_WINDOW_STATE_TYPE_SNAPPED;
         break;
+      case wm::WINDOW_STATE_TYPE_DOCKED:
+      case wm::WINDOW_STATE_TYPE_DOCKED_MINIMIZED:
+        active_window_state_type = ACTIVE_WINDOW_STATE_TYPE_DOCKED;
+        break;
       case wm::WINDOW_STATE_TYPE_DEFAULT:
       case wm::WINDOW_STATE_TYPE_NORMAL:
       case wm::WINDOW_STATE_TYPE_MINIMIZED: