Added UMA statistics for changing the active window via click or touch events.

ui/views/widget/desktop_aura/desktop_native_widget_aura.cc

 // Copyright (c) 2012 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 "ui/views/widget/desktop_aura/desktop_native_widget_aura.h"
 
 #include "base/bind.h"
 #include "base/trace_event/trace_event.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/client/cursor_client.h"
@@ skipping 38 matching lines @@
 #include "ui/views/widget/window_reorderer.h"
 #include "ui/views/window/native_frame_view.h"
 #include "ui/wm/core/compound_event_filter.h"
 #include "ui/wm/core/cursor_manager.h"
 #include "ui/wm/core/focus_controller.h"
 #include "ui/wm/core/input_method_event_filter.h"
 #include "ui/wm/core/native_cursor_manager.h"
 #include "ui/wm/core/shadow_controller.h"
 #include "ui/wm/core/shadow_types.h"
 #include "ui/wm/core/visibility_controller.h"
+#include "ui/wm/core/window_activation_pre_target_handler.h"
 #include "ui/wm/core/window_animations.h"
 #include "ui/wm/core/window_modality_controller.h"
 #include "ui/wm/public/activation_client.h"
 #include "ui/wm/public/drag_drop_client.h"
 
 #if defined(OS_WIN)
 #include "ui/base/win/shell.h"
 #include "ui/gfx/win/dpi.h"
 #endif
 
@@ skipping 244 matching lines @@
   root_window_event_filter_->RemoveHandler(input_method_event_filter_.get());
 
   window_tree_client_.reset();  // Uses host_->dispatcher() at destruction.
 
   capture_client_.reset();  // Uses host_->dispatcher() at destruction.
 
   // FocusController uses |content_window_|. Destroy it now so that we don't
   // have to worry about the possibility of FocusController attempting to use
   // |content_window_| after it's been destroyed but before all child windows
   // have been destroyed.
-  host_->window()->RemovePreTargetHandler(focus_client_.get());
+  host_->window()->RemovePreTargetHandler(
+      window_activation_pretarget_handler_.get());
+  window_activation_pretarget_handler_.reset();
   aura::client::SetFocusClient(host_->window(), NULL);
   aura::client::SetActivationClient(host_->window(), NULL);
   focus_client_.reset();
 
   host_->RemoveObserver(this);
   host_.reset();  // Uses input_method_event_filter_ at destruction.
   // WindowEventDispatcher owns |desktop_window_tree_host_|.
   desktop_window_tree_host_ = NULL;
   content_window_ = NULL;
 
@@ skipping 137 matching lines @@
 
   UpdateWindowTransparency();
 
   capture_client_.reset(new DesktopCaptureClient(host_->window()));
 
   wm::FocusController* focus_controller =
       new wm::FocusController(new DesktopFocusRules(content_window_));
   focus_client_.reset(focus_controller);
   aura::client::SetFocusClient(host_->window(), focus_controller);
   aura::client::SetActivationClient(host_->window(), focus_controller);
-  host_->window()->AddPreTargetHandler(focus_controller);
+  window_activation_pretarget_handler_.reset(

[sky, 2015/05/27 15:37:52]

I don't like separating out activation from the focus controller. It means you
either have to duplicate checks done in the focuscontroller (bad) or skip them
(worse).

I'm still not clear on what you hope to gain from these metrics, but why not add
the information you need to ActivationChangeObserver::OnWindowActivated?

+      new ::wm::WindowActivationPreTargetHandler(focus_client_.get()));
+  host_->window()->AddPreTargetHandler(
+      window_activation_pretarget_handler_.get());
 
   dispatcher_client_.reset(new DesktopDispatcherClient);
   aura::client::SetDispatcherClient(host_->window(),
                                     dispatcher_client_.get());
 
   position_client_.reset(new DesktopScreenPositionClient(host_->window()));
 
   InstallInputMethodEventFilter();
 
   drag_drop_client_ = desktop_window_tree_host_->CreateDragDropClient(
@@ skipping 753 matching lines @@
   if (cursor_reference_count_ == 0) {
     // We are the last DesktopNativeWidgetAura instance, and we are responsible
     // for cleaning up |cursor_manager_|.
     delete cursor_manager_;
     native_cursor_manager_ = NULL;
     cursor_manager_ = NULL;
   }
 }
 
 }  // namespace views