Add pretargethandler to exit overview mode on touch/click.

ash/desktop_background/desktop_background_view.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 "ash/desktop_background/desktop_background_view.h"
 
 #include <limits>
 
 #include "ash/ash_export.h"
 #include "ash/desktop_background/desktop_background_controller.h"
 #include "ash/desktop_background/desktop_background_widget_controller.h"
 #include "ash/desktop_background/user_wallpaper_delegate.h"
 #include "ash/display/display_manager.h"
 #include "ash/root_window_controller.h"
 #include "ash/session/session_state_delegate.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
+#include "ash/wm/overview/window_selector_controller.h"
 #include "ash/wm/window_animations.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/utf_string_conversions.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/compositor/layer.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/image/image.h"
 #include "ui/gfx/size_conversions.h"
 #include "ui/gfx/transform.h"
@@ skipping 37 matching lines @@
     transform.Scale(ui_scale, ui_scale);
     child->SetTransform(transform);
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LayerControlView);
 };
 
 }  // namespace
 
+namespace internal {
+
+// This event handler receives events in the pre-target phase and takes care of
+// the following:
+//   - Disabling overview mode on touch release.
+//   - Disabling overview mode on mouse release.
+class PreEventDispatchHandler : public ui::EventHandler {
+ public:
+  PreEventDispatchHandler() {}
+  virtual ~PreEventDispatchHandler() {}
+
+ private:
+  // ui::EventHandler:
+  virtual void OnMouseEvent(ui::MouseEvent* event) OVERRIDE {
+    CHECK_EQ(ui::EP_PRETARGET, event->phase());
+    if (event->handled())

[tdanderson, 2014/08/01 20:09:27]

Is there a particular reason you added this check in here since the last patch
set?

[rsadam, 2014/08/05 14:52:55]

I went back and looked at root_view.cc and this check is
there:https://code.google.com/p/chromium/codesearch#chromium/src/ui/views/widget/root_view.cc&l=68

I thought this meant that events could be sent to pretarget handlers, even if an
ancestor pretarget handler had dealt with the event.

+      return;
+    WindowSelectorController* controller =
+        Shell::GetInstance()->window_selector_controller();
+    if (event->type() == ui::ET_MOUSE_RELEASED && controller->IsSelecting()) {
+      controller->ToggleOverview();
+      event->StopPropagation();
+    }
+  }
+
+  virtual void OnTouchEvent(ui::TouchEvent* event) OVERRIDE {

[tdanderson, 2014/08/01 20:09:27]

Since you've changed to listening for gestures, this needs to be
OnGestureEvent(ui::GestureEvent* event) instead of OnTouchEvent().

[rsadam, 2014/08/05 14:52:54]

Done.

+    CHECK_EQ(ui::EP_PRETARGET, event->phase());
+    if (event->handled())
+      return;
+    WindowSelectorController* controller =
+        Shell::GetInstance()->window_selector_controller();
+    if (event->type() == ui::ET_GESTURE_TAP && controller->IsSelecting()) {
+      controller->ToggleOverview();
+      event->StopPropagation();
+    }
+  }
+
+  DISALLOW_COPY_AND_ASSIGN(PreEventDispatchHandler);
+};
+
+}  // namespace internal
+
 ////////////////////////////////////////////////////////////////////////////////
 // DesktopBackgroundView, public:
 
-DesktopBackgroundView::DesktopBackgroundView() {
+DesktopBackgroundView::DesktopBackgroundView()
+    : pre_dispatch_handler_(new internal::PreEventDispatchHandler()) {
   set_context_menu_controller(this);
+  AddPreTargetHandler(pre_dispatch_handler_.get());
 }
 
 DesktopBackgroundView::~DesktopBackgroundView() {

[bshe, 2014/08/05 11:38:28]

nit: do you need to remove the handler here?

[rsadam, 2014/08/05 14:52:55]

Done.

 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // DesktopBackgroundView, views::View overrides:
 
 void DesktopBackgroundView::OnPaint(gfx::Canvas* canvas) {
   // Scale the image while maintaining the aspect ratio, cropping as
   // necessary to fill the background. Ideally the image should be larger
   // than the largest display supported, if not we will scale and center it if
   // the layout is WALLPAPER_LAYOUT_CENTER_CROPPED.
@@ skipping 124 matching lines @@
     // Disable animation if transition to login screen from an empty background.
     wm::SetWindowVisibilityAnimationTransition(
         desktop_widget->GetNativeView(), wm::ANIMATE_NONE);
   }
 
   desktop_widget->SetBounds(params.parent->bounds());
   return desktop_widget;
 }
 
 }  // namespace ash