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

ui/aura/window.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/aura/window.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 184 matching lines @@
       user_data_(NULL),
       ignore_events_(false),
       // Don't notify newly added observers during notification. This causes
       // problems for code that adds an observer as part of an observer
       // notification (such as the workspace code).
       observers_(ObserverList<WindowObserver>::NOTIFY_EXISTING_ONLY) {
   set_target_handler(delegate_);
 }
 
 Window::~Window() {
-  if (layer()->owner() == this)
-    layer()->CompleteAllAnimations();
-  layer()->SuppressPaint();
+  if (layer()) {

[danakj, 2015/06/03 22:02:50]

Not having a layer means you made a Window but didn't call Init() on it. Fix the
callsite?

+    if (layer()->owner() == this)
+      layer()->CompleteAllAnimations();
+    layer()->SuppressPaint();
+  }
 
   // Let the delegate know we're in the processing of destroying.
   if (delegate_)
     delegate_->OnWindowDestroying(this);
   FOR_EACH_OBSERVER(WindowObserver, observers_, OnWindowDestroying(this));
 
   // While we are being destroyed, our target handler may also be in the
   // process of destruction or already destroyed, so do not forward any
   // input events at the ui::EP_TARGET phase.
   set_target_handler(nullptr);
@@ skipping 35 matching lines @@
 
   // Clear properties.
   for (std::map<const void*, Value>::const_iterator iter = prop_map_.begin();
        iter != prop_map_.end();
        ++iter) {
     if (iter->second.deallocator)
       (*iter->second.deallocator)(iter->second.value);
   }
   prop_map_.clear();
 
-  // The layer will either be destroyed by |layer_owner_|'s dtor, or by whoever
-  // acquired it.
-  layer()->set_delegate(NULL);
+  if (layer()) {
+    // The layer will either be destroyed by |layer_owner_|'s dtor, or by
+    // whoever acquired it.
+    layer()->set_delegate(NULL);
+  }
   DestroyLayer();
 }
 
 void Window::Init(ui::LayerType layer_type) {
   SetLayer(new ui::Layer(layer_type));
   layer()->SetVisible(false);
   layer()->set_delegate(this);
   UpdateLayerName();
   layer()->SetFillsBoundsOpaquely(!transparent_);
   Env::GetInstance()->NotifyWindowInitialized(this);
@@ skipping 1125 matching lines @@
       return window;
     if (offset)
       *offset += window->bounds().OffsetFromOrigin();
   }
   if (offset)
     *offset = gfx::Vector2d();
   return NULL;
 }
 
 }  // namespace aura