Add pretargethandler to exit overview mode on touch/click.

ash/desktop_background/desktop_background_view.cc

Index: ash/desktop_background/desktop_background_view.cc
diff --git a/ash/desktop_background/desktop_background_view.cc b/ash/desktop_background/desktop_background_view.cc
index d0e850c8889d714d825bb80ed3a1ef940299566d..64381685ef1e2d1a53b9a96ba3c1f93540875abc 100644
--- a/ash/desktop_background/desktop_background_view.cc
+++ b/ash/desktop_background/desktop_background_view.cc
@@ -15,6 +15,7 @@
 #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"
@@ -72,11 +73,55 @@ class LayerControlView : public views::View {
 
 }  // 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.