Migrate simple ash Shell metrics users.

ash/shelf/shelf_button_pressed_metric_tracker.cc

Index: ash/shelf/shelf_button_pressed_metric_tracker.cc
diff --git a/ash/shelf/shelf_button_pressed_metric_tracker.cc b/ash/shelf/shelf_button_pressed_metric_tracker.cc
index 00fab2cc57c0965dcb2519cb0e4567b8420a6403..096972d6ec74c3494615a68ba257d4dc5cd0f58a 100644
--- a/ash/shelf/shelf_button_pressed_metric_tracker.cc
+++ b/ash/shelf/shelf_button_pressed_metric_tracker.cc
@@ -4,8 +4,7 @@
 
 #include "ash/shelf/shelf_button_pressed_metric_tracker.h"
 
-#include "ash/metrics/user_metrics_recorder.h"
-#include "ash/shell.h"
+#include "ash/common/wm_shell.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/time/default_tick_clock.h"
 #include "ui/views/controls/button/button.h"
@@ -51,10 +50,10 @@ void ShelfButtonPressedMetricTracker::ButtonPressed(
 void ShelfButtonPressedMetricTracker::RecordButtonPressedSource(
     const ui::Event& event) {
   if (event.IsMouseEvent()) {
-    Shell::GetInstance()->metrics()->RecordUserMetricsAction(
+    WmShell::Get()->RecordUserMetricsAction(
         UMA_LAUNCHER_BUTTON_PRESSED_WITH_MOUSE);
   } else if (event.IsGestureEvent()) {
-    Shell::GetInstance()->metrics()->RecordUserMetricsAction(
+    WmShell::Get()->RecordUserMetricsAction(
         UMA_LAUNCHER_BUTTON_PRESSED_WITH_TOUCH);
   }
 }
@@ -66,16 +65,13 @@ void ShelfButtonPressedMetricTracker::RecordButtonPressedAction(
     case ShelfItemDelegate::kAppListMenuShown:
       break;
     case ShelfItemDelegate::kNewWindowCreated:
-      Shell::GetInstance()->metrics()->RecordUserMetricsAction(
-          UMA_LAUNCHER_LAUNCH_TASK);
+      WmShell::Get()->RecordUserMetricsAction(UMA_LAUNCHER_LAUNCH_TASK);
       break;
     case ShelfItemDelegate::kExistingWindowActivated:
-      Shell::GetInstance()->metrics()->RecordUserMetricsAction(
-          UMA_LAUNCHER_SWITCH_TASK);
+      WmShell::Get()->RecordUserMetricsAction(UMA_LAUNCHER_SWITCH_TASK);
       break;
     case ShelfItemDelegate::kExistingWindowMinimized:
-      Shell::GetInstance()->metrics()->RecordUserMetricsAction(
-          UMA_LAUNCHER_MINIMIZE_TASK);
+      WmShell::Get()->RecordUserMetricsAction(UMA_LAUNCHER_MINIMIZE_TASK);
       break;
   }
 }