Add UMA metrics for window selection and overview.

ash/wm/overview/window_overview.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/wm/overview/window_overview.h"
 
 #include <algorithm>
 
 #include "ash/screen_ash.h"
 #include "ash/shell.h"
+#include "ash/shell_delegate.h"
 #include "ash/shell_window_ids.h"
 #include "ash/wm/overview/window_selector.h"
 #include "ash/wm/overview/window_selector_item.h"
+#include "base/metrics/histogram.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
 #include "ui/compositor/scoped_layer_animation_settings.h"
 #include "ui/events/event.h"
 #include "ui/views/widget/widget.h"
 
 namespace ash {
 
 namespace {
@@ skipping 20 matching lines @@
   const aura::Window* target;
 };
 
 }  // namespace
 
 WindowOverview::WindowOverview(WindowSelector* window_selector,
                                WindowSelectorItemList* windows,
                                aura::RootWindow* single_root_window)
     : window_selector_(window_selector),
       windows_(windows),
-      single_root_window_(single_root_window) {
+      single_root_window_(single_root_window),
+      overview_start_time_(base::Time::Now()) {
   PositionWindows();
   ash::Shell::GetInstance()->AddPreTargetHandler(this);
+  Shell* shell = Shell::GetInstance();
+  shell->delegate()->RecordUserMetricsAction(UMA_WINDOW_OVERVIEW);
 }
 
 WindowOverview::~WindowOverview() {
   ash::Shell::GetInstance()->RemovePreTargetHandler(this);
+  UMA_HISTOGRAM_MEDIUM_TIMES(
+      "Ash.WindowSelector.TimeInOverview",
+      base::Time::Now() - overview_start_time_);
 }
 
 void WindowOverview::SetSelection(size_t index) {
   DCHECK_LT(index, windows_->size());
   gfx::Rect target_bounds = (*windows_)[index]->bounds();
   target_bounds.Inset(-kWindowOverviewSelectionPadding,
                       -kWindowOverviewSelectionPadding);
 
   if (selection_widget_) {
     // If the selection widget is already active, animate to the new bounds.
@@ skipping 166 matching lines @@
       views::Background::CreateSolidBackground(kWindowOverviewSelectionColor));
   selection_widget_->SetContentsView(content_view);
   selection_widget_->GetNativeWindow()->parent()->StackChildAtBottom(
       selection_widget_->GetNativeWindow());
   selection_widget_->Show();
   selection_widget_->GetNativeWindow()->layer()->SetOpacity(
       kWindowOverviewSelectionOpacity);
 }
 
 }  // namespace ash