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

ui/wm/core/window_activation_pre_target_handler_observer.h

Index: ui/wm/core/window_activation_pre_target_handler_observer.h
diff --git a/ui/wm/core/window_activation_pre_target_handler_observer.h b/ui/wm/core/window_activation_pre_target_handler_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..c078fa7c9f3ca2f9867acb7e2d6189d6ace30adc
--- /dev/null
+++ b/ui/wm/core/window_activation_pre_target_handler_observer.h
@@ -0,0 +1,34 @@
+// Copyright 2015 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.
+
+#ifndef UI_WM_CORE_WINDOW_ACTIVATION_PRE_TARGET_HANDLER_OBSERVER_H_
+#define UI_WM_CORE_WINDOW_ACTIVATION_PRE_TARGET_HANDLER_OBSERVER_H_
+
+#include "base/macros.h"
+#include "ui/wm/wm_export.h"
+
+namespace aura {
+class Window;
+}  // namespace aura
+
+namespace wm {
+
+class WM_EXPORT WindowActivationPreTargetHandlerObserver {
+ public:
+  WindowActivationPreTargetHandlerObserver();
+  virtual ~WindowActivationPreTargetHandlerObserver();
+
+  virtual void BeforeWindowActivatedByPreTargetHandler() = 0;

[tdanderson, 2015/05/26 21:13:53]

I don't think you need to say "ByPreTargetHandler" in your method names here.

+
+  virtual void OnWindowActivatedByPreTargetHandler(
+      aura::Window* gained_active,
+      aura::Window* lost_active) = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(WindowActivationPreTargetHandlerObserver);
+};
+
+}  // namespace wm
+
+#endif  // UI_WM_CORE_WINDOW_ACTIVATION_PRE_TARGET_HANDLER_OBSERVER_H_