events: Change gesture-event handler in EventHandler to not return any values.

The EventHandler overriddes should mark the event as having been processed
(Event::SetHandled) when the event triggered an action, or stop the propagation
of the event (Event::StopPropagation) as appropriate (when the handler destroyed
the event-target, for example).

BUG=163618

Review URL: https://codereview.chromium.org/11280290

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@170890 0039d316-1c4b-4281-b951-d872f2087c98

31 files changed, 97 insertions, 92 deletions

diff --git a/ash/drag_drop/drag_drop_controller.cc b/ash/drag_drop/drag_drop_controller.cc
index db0e213..cf6135e 100644
--- a/ash/drag_drop/drag_drop_controller.cc
+++ b/ash/drag_drop/drag_drop_controller.cc
@@ -332,14 +332,17 @@ ui::EventResult DragDropController::OnTouchEvent(ui::TouchEvent* event) {
   return ui::ER_UNHANDLED;
 }
 
-ui::EventResult DragDropController::OnGestureEvent(ui::GestureEvent* event) {
+void DragDropController::OnGestureEvent(ui::GestureEvent* event) {
   if (!IsDragDropInProgress())
-    return ui::ER_UNHANDLED;
+    return;
 
   // If current drag session was not started by touch, dont process this touch
   // event, but consume it so it does not interfere with current drag session.
-  if (current_drag_event_source_ != ui::DragDropTypes::DRAG_EVENT_SOURCE_TOUCH)
-    return ui::ER_CONSUMED;
+  if (current_drag_event_source_ !=
+      ui::DragDropTypes::DRAG_EVENT_SOURCE_TOUCH) {
+    event->StopPropagation();
+    return;
+  }
 
   // Apply kTouchDragImageVerticalOffset to the location.
   ui::GestureEvent touch_offset_event(*event,
@@ -356,7 +359,8 @@ ui::EventResult DragDropController::OnGestureEvent(ui::GestureEvent* event) {
       drag_drop_tracker_->GetTarget(touch_offset_event);
   if (!translated_target) {
     DragCancel();
-    return ui::ER_HANDLED;
+    event->SetHandled();
+    return;
   }
   scoped_ptr<ui::LocatedEvent> translated_event(
       drag_drop_tracker_->ConvertEvent(translated_target, touch_offset_event));
@@ -384,7 +388,7 @@ ui::EventResult DragDropController::OnGestureEvent(ui::GestureEvent* event) {
     default:
       break;
   }
-  return ui::ER_HANDLED;
+  event->SetHandled();
 }
 
 void DragDropController::OnWindowDestroyed(aura::Window* window) {
diff --git a/ash/drag_drop/drag_drop_controller.h b/ash/drag_drop/drag_drop_controller.h
index f38b522..6fe58a1 100644
--- a/ash/drag_drop/drag_drop_controller.h
+++ b/ash/drag_drop/drag_drop_controller.h
@@ -68,7 +68,7 @@ class ASH_EXPORT DragDropController
   virtual ui::EventResult OnKeyEvent(ui::KeyEvent* event) OVERRIDE;
   virtual ui::EventResult OnMouseEvent(ui::MouseEvent* event) OVERRIDE;
   virtual ui::EventResult OnTouchEvent(ui::TouchEvent* event) OVERRIDE;
-  virtual ui::EventResult OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
+  virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
 
   // Overridden from aura::WindowObserver.
   virtual void OnWindowDestroyed(aura::Window* window) OVERRIDE;
diff --git a/ash/drag_drop/drag_drop_controller_unittest.cc b/ash/drag_drop/drag_drop_controller_unittest.cc
index 5847fdc..14a25c6 100644
--- a/ash/drag_drop/drag_drop_controller_unittest.cc
+++ b/ash/drag_drop/drag_drop_controller_unittest.cc
@@ -85,10 +85,10 @@ class DragTestView : public views::View {
     return true;
   }
 
-  ui::EventResult OnGestureEvent(ui::GestureEvent* event) OVERRIDE {
+  void OnGestureEvent(ui::GestureEvent* event) OVERRIDE {
     if (event->type() == ui::ET_GESTURE_LONG_TAP)
       long_tap_received_ = true;
-    return ui::ER_UNHANDLED;
+    return;
   }
 
   bool GetDropFormats(int* formats,
diff --git a/ash/launcher/launcher_button.cc b/ash/launcher/launcher_button.cc
index b4c4f9b..be5e381 100644
--- a/ash/launcher/launcher_button.cc
+++ b/ash/launcher/launcher_button.cc
@@ -304,7 +304,7 @@ void LauncherButton::OnBlur() {
   CustomButton::OnBlur();
 }
 
-ui::EventResult LauncherButton::OnGestureEvent(ui::GestureEvent* event) {
+void LauncherButton::OnGestureEvent(ui::GestureEvent* event) {
   switch (event->type()) {
     case ui::ET_GESTURE_TAP_DOWN:
       AddState(STATE_HOVERED);
@@ -314,14 +314,17 @@ ui::EventResult LauncherButton::OnGestureEvent(ui::GestureEvent* event) {
       return CustomButton::OnGestureEvent(event);
     case ui::ET_GESTURE_SCROLL_BEGIN:
       host_->PointerPressedOnButton(this, LauncherButtonHost::TOUCH, *event);
-      return ui::ER_CONSUMED;
+      event->SetHandled();
+      return;
     case ui::ET_GESTURE_SCROLL_UPDATE:
       host_->PointerDraggedOnButton(this, LauncherButtonHost::TOUCH, *event);
-      return ui::ER_CONSUMED;
+      event->SetHandled();
+      return;
     case ui::ET_GESTURE_SCROLL_END:
     case ui::ET_SCROLL_FLING_START:
       host_->PointerReleasedOnButton(this, LauncherButtonHost::TOUCH, false);
-      return ui::ER_CONSUMED;
+      event->SetHandled();
+      return;
     default:
       return CustomButton::OnGestureEvent(event);
   }
diff --git a/ash/launcher/launcher_button.h b/ash/launcher/launcher_button.h
index f4c0755..c46b209 100644
--- a/ash/launcher/launcher_button.h
+++ b/ash/launcher/launcher_button.h
@@ -91,7 +91,7 @@ class LauncherButton : public views::CustomButton {
   virtual void OnBlur() OVERRIDE;
 
   // ui::EventHandler overrides:
-  virtual ui::EventResult OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
+  virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
 
   // Sets the icon image with a shadow.
   void SetShadowedImage(const gfx::ImageSkia& bitmap);
diff --git a/ash/launcher/launcher_tooltip_manager.cc b/ash/launcher/launcher_tooltip_manager.cc
index 4263bd6..05e8ccc 100644
--- a/ash/launcher/launcher_tooltip_manager.cc
+++ b/ash/launcher/launcher_tooltip_manager.cc
@@ -302,15 +302,12 @@ ui::EventResult LauncherTooltipManager::OnTouchEvent(ui::TouchEvent* event) {
   return ui::ER_UNHANDLED;
 }
 
-ui::EventResult LauncherTooltipManager::OnGestureEvent(
-    ui::GestureEvent* event) {
+void LauncherTooltipManager::OnGestureEvent(ui::GestureEvent* event) {
   if (widget_ && widget_->IsVisible()) {
     // Because this mouse event may arrive to |view_|, here we just schedule
     // the closing event rather than directly calling Close().
     CloseSoon();
   }
-
-  return ui::ER_UNHANDLED;
 }
 
 void LauncherTooltipManager::OnSessionStateEvent(
diff --git a/ash/launcher/launcher_tooltip_manager.h b/ash/launcher/launcher_tooltip_manager.h
index 5bbab27..ee3395f 100644
--- a/ash/launcher/launcher_tooltip_manager.h
+++ b/ash/launcher/launcher_tooltip_manager.h
@@ -75,7 +75,7 @@ protected:
   // ui::EventHandler overrides:
   virtual ui::EventResult OnMouseEvent(ui::MouseEvent* event) OVERRIDE;
   virtual ui::EventResult OnTouchEvent(ui::TouchEvent* event) OVERRIDE;
-  virtual ui::EventResult OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
+  virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
 
   // SessionStateObserver override:
   virtual void OnSessionStateEvent(SessionStateObserver::EventType event)
diff --git a/ash/launcher/launcher_tooltip_manager_unittest.cc b/ash/launcher/launcher_tooltip_manager_unittest.cc
index 94b4c28..39ba6dc 100644
--- a/ash/launcher/launcher_tooltip_manager_unittest.cc
+++ b/ash/launcher/launcher_tooltip_manager_unittest.cc
@@ -184,8 +184,8 @@ TEST_F(LauncherTooltipManagerTest, ShouldHideForEvents) {
       base::TimeDelta::FromMilliseconds(base::Time::Now().ToDoubleT() * 1000),
       ui::GestureEventDetails(ui::ET_GESTURE_BEGIN, 0.0f, 0.0f), 0);
   SetEventTarget(tooltip_widget->GetNativeWindow(), &gesture_event);
-  EXPECT_EQ(ui::ER_UNHANDLED,
-            event_handler->OnGestureEvent(&gesture_event));
+  event_handler->OnGestureEvent(&gesture_event);
+  EXPECT_FALSE(gesture_event.handled());
   RunAllPendingInMessageLoop();
   EXPECT_FALSE(TooltipIsVisible());
 }
diff --git a/ash/launcher/launcher_view.cc b/ash/launcher/launcher_view.cc
index f51da7a..4148c87 100644
--- a/ash/launcher/launcher_view.cc
+++ b/ash/launcher/launcher_view.cc
@@ -788,9 +788,9 @@ views::FocusTraversable* LauncherView::GetPaneFocusTraversable() {
   return this;
 }
 
-ui::EventResult LauncherView::OnGestureEvent(ui::GestureEvent* event) {
-  return gesture_handler_.ProcessGestureEvent(*event) ?
-      ui::ER_CONSUMED : ui::ER_UNHANDLED;
+void LauncherView::OnGestureEvent(ui::GestureEvent* event) {
+  if (gesture_handler_.ProcessGestureEvent(*event))
+    event->StopPropagation();
 }
 
 void LauncherView::LauncherItemAdded(int model_index) {
diff --git a/ash/launcher/launcher_view.h b/ash/launcher/launcher_view.h
index ece7ba6..ff5fd6a 100644
--- a/ash/launcher/launcher_view.h
+++ b/ash/launcher/launcher_view.h
@@ -184,7 +184,7 @@ class ASH_EXPORT LauncherView : public views::View,
   virtual FocusTraversable* GetPaneFocusTraversable() OVERRIDE;
 
   // Overridden from ui::EventHandler:
-  virtual ui::EventResult OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
+  virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
 
   // Overridden from LauncherModelObserver:
   virtual void LauncherItemAdded(int model_index) OVERRIDE;
diff --git a/ash/system/status_area_widget_delegate.cc b/ash/system/status_area_widget_delegate.cc
index 94d6ea5..f82ec13 100644
--- a/ash/system/status_area_widget_delegate.cc
+++ b/ash/system/status_area_widget_delegate.cc
@@ -61,12 +61,11 @@ const views::Widget* StatusAreaWidgetDelegate::GetWidget() const {
   return View::GetWidget();
 }
 
-ui::EventResult StatusAreaWidgetDelegate::OnGestureEvent(
-    ui::GestureEvent* event) {
+void StatusAreaWidgetDelegate::OnGestureEvent(ui::GestureEvent* event) {
   if (gesture_handler_.ProcessGestureEvent(*event))
-    return ui::ER_CONSUMED;
-
-  return views::AccessiblePaneView::OnGestureEvent(event);
+    event->StopPropagation();
+  else
+    views::AccessiblePaneView::OnGestureEvent(event);
 }
 
 bool StatusAreaWidgetDelegate::CanActivate() const {
diff --git a/ash/system/status_area_widget_delegate.h b/ash/system/status_area_widget_delegate.h
index 7c56ff3..f924231 100644
--- a/ash/system/status_area_widget_delegate.h
+++ b/ash/system/status_area_widget_delegate.h
@@ -43,7 +43,7 @@ class ASH_EXPORT StatusAreaWidgetDelegate : public views::AccessiblePaneView,
   virtual const views::Widget* GetWidget() const OVERRIDE;
 
   // Overridden from ui::EventHandler:
-  virtual ui::EventResult OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
+  virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
 
   // views::WidgetDelegate overrides:
   virtual bool CanActivate() const OVERRIDE;
diff --git a/ash/system/tray/tray_notification_view.cc b/ash/system/tray/tray_notification_view.cc
index 2c4929b..1565fd7 100644
--- a/ash/system/tray/tray_notification_view.cc
+++ b/ash/system/tray/tray_notification_view.cc
@@ -124,13 +124,14 @@ bool TrayNotificationView::OnMousePressed(const ui::MouseEvent& event) {
   return true;
 }
 
-ui::EventResult TrayNotificationView::OnGestureEvent(ui::GestureEvent* event) {
-  if (SlideOutView::OnGestureEvent(event) == ui::ER_CONSUMED)
-    return ui::ER_CONSUMED;
+void TrayNotificationView::OnGestureEvent(ui::GestureEvent* event) {
+  SlideOutView::OnGestureEvent(event);
+  if (event->handled())
+    return;
   if (event->type() != ui::ET_GESTURE_TAP)
-    return ui::ER_UNHANDLED;
+    return;
   HandleClickAction();
-  return ui::ER_CONSUMED;
+  event->SetHandled();
 }
 
 void TrayNotificationView::OnClose() {
diff --git a/ash/system/tray/tray_notification_view.h b/ash/system/tray/tray_notification_view.h
index 059e5c6..84ee9ac 100644
--- a/ash/system/tray/tray_notification_view.h
+++ b/ash/system/tray/tray_notification_view.h
@@ -59,7 +59,7 @@ class TrayNotificationView : public views::SlideOutView,
   virtual bool OnMousePressed(const ui::MouseEvent& event) OVERRIDE;
 
   // Overridden from ui::EventHandler.
-  virtual ui::EventResult OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
+  virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
 
  protected:
   // Called when the close button is pressed. Does nothing by default.
diff --git a/ash/system/tray/tray_views.cc b/ash/system/tray/tray_views.cc
index ca7e625..522ca71 100644
--- a/ash/system/tray/tray_views.cc
+++ b/ash/system/tray/tray_views.cc
@@ -182,12 +182,9 @@ void ActionableView::OnPaintFocusBorder(gfx::Canvas* canvas) {
     DrawBorder(canvas, GetLocalBounds());
 }
 
-ui::EventResult ActionableView::OnGestureEvent(ui::GestureEvent* event) {
-  if (event->type() == ui::ET_GESTURE_TAP) {
-    return PerformAction(*event) ? ui::ER_CONSUMED :
-                                  ui::ER_UNHANDLED;
-  }
-  return ui::ER_UNHANDLED;
+void ActionableView::OnGestureEvent(ui::GestureEvent* event) {
+  if (event->type() == ui::ET_GESTURE_TAP && PerformAction(*event))
+    event->SetHandled();
 }
 
 void ActionableView::GetAccessibleState(ui::AccessibleViewState* state) {
diff --git a/ash/system/tray/tray_views.h b/ash/system/tray/tray_views.h
index 84e8d17..92be6dd 100644
--- a/ash/system/tray/tray_views.h
+++ b/ash/system/tray/tray_views.h
@@ -82,7 +82,7 @@ class ASH_EXPORT ActionableView : public views::View {
   virtual void OnPaintFocusBorder(gfx::Canvas* canvas) OVERRIDE;
 
   // Overridden from ui::EventHandler.
-  virtual ui::EventResult OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
+  virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
 
  private:
   string16 accessible_name_;
diff --git a/ash/wm/activation_controller.cc b/ash/wm/activation_controller.cc
index 0810d51..337979b 100644
--- a/ash/wm/activation_controller.cc
+++ b/ash/wm/activation_controller.cc
@@ -286,12 +286,11 @@ ui::EventResult ActivationController::OnTouchEvent(ui::TouchEvent* event) {
   return ui::ER_UNHANDLED;
 }
 
-ui::EventResult ActivationController::OnGestureEvent(ui::GestureEvent* event) {
+void ActivationController::OnGestureEvent(ui::GestureEvent* event) {
   if (event->type() == ui::ET_GESTURE_BEGIN &&
       event->details().touch_points() == 1) {
     FocusWindowWithEvent(event);
   }
-  return ui::ER_UNHANDLED;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/ash/wm/activation_controller.h b/ash/wm/activation_controller.h
index 3b439ab..6af15ed 100644
--- a/ash/wm/activation_controller.h
+++ b/ash/wm/activation_controller.h
@@ -77,7 +77,7 @@ class ASH_EXPORT ActivationController
   virtual ui::EventResult OnMouseEvent(ui::MouseEvent* event) OVERRIDE;
   virtual ui::EventResult OnScrollEvent(ui::ScrollEvent* event) OVERRIDE;
   virtual ui::EventResult OnTouchEvent(ui::TouchEvent* event) OVERRIDE;
-  virtual ui::EventResult OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
+  virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
 
   // Implementation of ActivateWindow() with an Event.
   void ActivateWindowWithEvent(aura::Window* window,
diff --git a/ash/wm/app_list_controller.cc b/ash/wm/app_list_controller.cc
index 2abb2b9..e0785c8 100644
--- a/ash/wm/app_list_controller.cc
+++ b/ash/wm/app_list_controller.cc
@@ -253,10 +253,9 @@ ui::EventResult AppListController::OnMouseEvent(ui::MouseEvent* event) {
   return ui::ER_UNHANDLED;
 }
 
-ui::EventResult AppListController::OnGestureEvent(ui::GestureEvent* event) {
+void AppListController::OnGestureEvent(ui::GestureEvent* event) {
   if (event->type() == ui::ET_GESTURE_TAP)
     ProcessLocatedEvent(event);
-  return ui::ER_UNHANDLED;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/ash/wm/app_list_controller.h b/ash/wm/app_list_controller.h
index 0446791..6f08a3f 100644
--- a/ash/wm/app_list_controller.h
+++ b/ash/wm/app_list_controller.h
@@ -76,7 +76,7 @@ class AppListController : public views::corewm::FocusChangeShim,
 
   // ui::EventHandler overrides:
   virtual ui::EventResult OnMouseEvent(ui::MouseEvent* event) OVERRIDE;
-  virtual ui::EventResult OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
+  virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
 
   // aura::client::FocusChangeObserver overrides:
   virtual void OnWindowFocused(aura::Window* window) OVERRIDE;
diff --git a/ash/wm/system_gesture_event_filter.cc b/ash/wm/system_gesture_event_filter.cc
index 5e40f93..57aecd4 100644
--- a/ash/wm/system_gesture_event_filter.cc
+++ b/ash/wm/system_gesture_event_filter.cc
@@ -72,8 +72,7 @@ ui::EventResult SystemGestureEventFilter::OnTouchEvent(ui::TouchEvent* event) {
   return ui::ER_UNHANDLED;
 }
 
-ui::EventResult SystemGestureEventFilter::OnGestureEvent(
-    ui::GestureEvent* event) {
+void SystemGestureEventFilter::OnGestureEvent(ui::GestureEvent* event) {
   aura::Window* target = static_cast<aura::Window*>(event->target());
   touch_uma_.RecordGestureEvent(target, *event);
   long_press_affordance_->ProcessEvent(target, event,
@@ -81,18 +80,21 @@ ui::EventResult SystemGestureEventFilter::OnGestureEvent(
 
   if (!target || target == target->GetRootWindow()) {
     bezel_gestures_->ProcessGestureEvent(target, *event);
-    return ui::ER_CONSUMED;
+    event->StopPropagation();
+    return;
   }
 
-  if (two_finger_drag_->ProcessGestureEvent(target, *event))
-    return ui::ER_CONSUMED;
+  if (two_finger_drag_->ProcessGestureEvent(target, *event)) {
+    event->StopPropagation();
+    return;
+  }
 
   if (!system_gestures_enabled_)
-    return ui::ER_UNHANDLED;
+    return;
 
   aura::Window* system_target = GetTargetForSystemGestureEvent(target);
   if (!system_target)
-    return ui::ER_UNHANDLED;
+    return;
 
   RootWindowController* root_controller =
       GetRootWindowController(system_target->GetRootWindow());
@@ -108,9 +110,9 @@ ui::EventResult SystemGestureEventFilter::OnGestureEvent(
       ash::AcceleratorController* accelerator =
           ash::Shell::GetInstance()->accelerator_controller();
       if (accelerator->PerformAction(CYCLE_FORWARD_MRU, ui::Accelerator()))
-        return ui::ER_CONSUMED;
+        event->StopPropagation();
     }
-    return ui::ER_UNHANDLED;
+    return;
   }
 
   WindowPinchHandlerMap::iterator find = pinch_handlers_.find(system_target);
@@ -119,18 +121,16 @@ ui::EventResult SystemGestureEventFilter::OnGestureEvent(
         (*find).second->ProcessGestureEvent(*event);
     if (status == SYSTEM_GESTURE_END)
       ClearGestureHandlerForWindow(system_target);
-    return ui::ER_CONSUMED;
+    event->StopPropagation();
   } else {
     if (event->type() == ui::ET_GESTURE_BEGIN &&
         event->details().touch_points() >=
         SystemPinchHandler::kSystemGesturePoints) {
       pinch_handlers_[system_target] = new SystemPinchHandler(system_target);
       system_target->AddObserver(this);
-      return ui::ER_CONSUMED;
+      event->StopPropagation();
     }
   }
-
-  return ui::ER_UNHANDLED;
 }
 
 void SystemGestureEventFilter::OnWindowVisibilityChanged(aura::Window* window,
diff --git a/ash/wm/system_gesture_event_filter.h b/ash/wm/system_gesture_event_filter.h
index 8d7843f..961929e 100644
--- a/ash/wm/system_gesture_event_filter.h
+++ b/ash/wm/system_gesture_event_filter.h
@@ -47,7 +47,7 @@ class SystemGestureEventFilter : public ui::EventHandler,
   // Overridden from ui::EventHandler:
   virtual ui::EventResult OnMouseEvent(ui::MouseEvent* event) OVERRIDE;
   virtual ui::EventResult OnTouchEvent(ui::TouchEvent* event) OVERRIDE;
-  virtual ui::EventResult OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
+  virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
 
   // Overridden from aura::WindowObserver.
   virtual void OnWindowVisibilityChanged(aura::Window* window,
diff --git a/ash/wm/toplevel_window_event_handler.cc b/ash/wm/toplevel_window_event_handler.cc
index 4f5ad28..db7acb4 100644
--- a/ash/wm/toplevel_window_event_handler.cc
+++ b/ash/wm/toplevel_window_event_handler.cc
@@ -156,11 +156,10 @@ ui::EventResult ToplevelWindowEventHandler::OnMouseEvent(
   return ui::ER_UNHANDLED;
 }
 
-ui::EventResult ToplevelWindowEventHandler::OnGestureEvent(
-    ui::GestureEvent* event) {
+void ToplevelWindowEventHandler::OnGestureEvent(ui::GestureEvent* event) {
   aura::Window* target = static_cast<aura::Window*>(event->target());
   if (!target->delegate())
-    return ui::ER_UNHANDLED;
+    return;
 
   switch (event->type()) {
     case ui::ET_GESTURE_SCROLL_BEGIN: {
@@ -168,7 +167,7 @@ ui::EventResult ToplevelWindowEventHandler::OnGestureEvent(
           target->delegate()->GetNonClientComponent(event->location());
       if (WindowResizer::GetBoundsChangeForWindowComponent(component) == 0) {
         window_resizer_.reset();
-        return ui::ER_UNHANDLED;
+        return;
       }
       in_gesture_drag_ = true;
       gfx::Point location_in_parent(
@@ -178,14 +177,14 @@ ui::EventResult ToplevelWindowEventHandler::OnGestureEvent(
     }
     case ui::ET_GESTURE_SCROLL_UPDATE: {
       if (!in_gesture_drag_)
-        return ui::ER_UNHANDLED;
+        return;
       HandleDrag(target, event);
       break;
     }
     case ui::ET_GESTURE_SCROLL_END:
     case ui::ET_SCROLL_FLING_START: {
       if (!in_gesture_drag_)
-        return ui::ER_UNHANDLED;
+        return;
 
       CompleteDrag(DRAG_COMPLETE, event->flags());
       if (in_move_loop_) {
@@ -194,15 +193,17 @@ ui::EventResult ToplevelWindowEventHandler::OnGestureEvent(
       }
       in_gesture_drag_ = false;
 
-      if (event->type() == ui::ET_GESTURE_SCROLL_END)
-        return ui::ER_CONSUMED;
+      if (event->type() == ui::ET_GESTURE_SCROLL_END) {
+        event->StopPropagation();
+        return;
+      }
 
       int component =
           target->delegate()->GetNonClientComponent(event->location());
       if (WindowResizer::GetBoundsChangeForWindowComponent(component) == 0)
-        return ui::ER_UNHANDLED;
+        return;
       if (!wm::IsWindowNormal(target))
-        return ui::ER_UNHANDLED;
+        return;
 
       if (fabs(event->details().velocity_y()) >
           kMinVertVelocityForWindowMinimize) {
@@ -225,10 +226,10 @@ ui::EventResult ToplevelWindowEventHandler::OnGestureEvent(
       break;
     }
     default:
-      return ui::ER_UNHANDLED;
+      return;
   }
 
-  return ui::ER_CONSUMED;
+  event->StopPropagation();
 }
 
 aura::client::WindowMoveResult ToplevelWindowEventHandler::RunMoveLoop(
diff --git a/ash/wm/toplevel_window_event_handler.h b/ash/wm/toplevel_window_event_handler.h
index dc2c6d5..7b1a0b5 100644
--- a/ash/wm/toplevel_window_event_handler.h
+++ b/ash/wm/toplevel_window_event_handler.h
@@ -40,7 +40,7 @@ class ASH_EXPORT ToplevelWindowEventHandler
   // Overridden from ui::EventHandler:
   virtual ui::EventResult OnKeyEvent(ui::KeyEvent* event) OVERRIDE;
   virtual ui::EventResult OnMouseEvent(ui::MouseEvent* event) OVERRIDE;
-  virtual ui::EventResult OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
+  virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
 
   // Overridden form aura::client::WindowMoveClient:
   virtual aura::client::WindowMoveResult RunMoveLoop(
diff --git a/ash/wm/user_activity_detector.cc b/ash/wm/user_activity_detector.cc
index f245d55..ee6a2b7 100644
--- a/ash/wm/user_activity_detector.cc
+++ b/ash/wm/user_activity_detector.cc
@@ -58,9 +58,8 @@ ui::EventResult UserActivityDetector::OnTouchEvent(ui::TouchEvent* event) {
   return ui::ER_UNHANDLED;
 }
 
-ui::EventResult UserActivityDetector::OnGestureEvent(ui::GestureEvent* event) {
+void UserActivityDetector::OnGestureEvent(ui::GestureEvent* event) {
   MaybeNotify();
-  return ui::ER_UNHANDLED;
 }
 
 void UserActivityDetector::MaybeNotify() {
diff --git a/ash/wm/user_activity_detector.h b/ash/wm/user_activity_detector.h
index a555034..b28b9ec 100644
--- a/ash/wm/user_activity_detector.h
+++ b/ash/wm/user_activity_detector.h
@@ -39,7 +39,7 @@ class ASH_EXPORT UserActivityDetector : public ui::EventHandler {
   virtual ui::EventResult OnMouseEvent(ui::MouseEvent* event) OVERRIDE;
   virtual ui::EventResult OnScrollEvent(ui::ScrollEvent* event) OVERRIDE;
   virtual ui::EventResult OnTouchEvent(ui::TouchEvent* event) OVERRIDE;
-  virtual ui::EventResult OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
+  virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
 
  private:
   // Notifies observers if enough time has passed since the last notification.
diff --git a/ash/wm/user_activity_detector_unittest.cc b/ash/wm/user_activity_detector_unittest.cc
index 14c48a1..2aa0ef5f 100644
--- a/ash/wm/user_activity_detector_unittest.cc
+++ b/ash/wm/user_activity_detector_unittest.cc
@@ -127,7 +127,8 @@ TEST_F(UserActivityDetectorTest, Basic) {
       base::TimeDelta::FromMilliseconds(base::Time::Now().ToDoubleT() * 1000),
       ui::GestureEventDetails(ui::ET_GESTURE_TAP, 0, 0), 0U);
   SetEventTarget(window.get(), &gesture_event);
-  EXPECT_FALSE(detector_->OnGestureEvent(&gesture_event));
+  detector_->OnGestureEvent(&gesture_event);
+  EXPECT_FALSE(gesture_event.handled());
   EXPECT_EQ(1, observer_->num_invocations());
   observer_->reset_stats();
 }
diff --git a/ash/wm/workspace/frame_maximize_button.cc b/ash/wm/workspace/frame_maximize_button.cc
index 2d2a57a..a1c8ca9 100644
--- a/ash/wm/workspace/frame_maximize_button.cc
+++ b/ash/wm/workspace/frame_maximize_button.cc
@@ -245,11 +245,12 @@ void FrameMaximizeButton::OnMouseCaptureLost() {
   ImageButton::OnMouseCaptureLost();
 }
 
-ui::EventResult FrameMaximizeButton::OnGestureEvent(ui::GestureEvent* event) {
+void FrameMaximizeButton::OnGestureEvent(ui::GestureEvent* event) {
   if (event->type() == ui::ET_GESTURE_TAP_DOWN) {
     is_snap_enabled_ = true;
     ProcessStartEvent(*event);
-    return ui::ER_CONSUMED;
+    event->SetHandled();
+    return;
   }
 
   if (event->type() == ui::ET_GESTURE_TAP ||
@@ -261,7 +262,8 @@ ui::EventResult FrameMaximizeButton::OnGestureEvent(ui::GestureEvent* event) {
     if (event->type() == ui::ET_GESTURE_TAP)
       snap_type_ = SnapTypeForLocation(event->location());
     ProcessEndEvent(*event);
-    return ui::ER_CONSUMED;
+    event->SetHandled();
+    return;
   }
 
   if (is_snap_enabled_) {
@@ -272,17 +274,19 @@ ui::EventResult FrameMaximizeButton::OnGestureEvent(ui::GestureEvent* event) {
       ProcessUpdateEvent(*event);
       snap_type_ = SnapTypeForLocation(event->location());
       ProcessEndEvent(*event);
-      return ui::ER_CONSUMED;
+      event->SetHandled();
+      return;
     }
 
     if (event->type() == ui::ET_GESTURE_SCROLL_UPDATE ||
         event->type() == ui::ET_GESTURE_SCROLL_BEGIN) {
       ProcessUpdateEvent(*event);
-      return ui::ER_CONSUMED;
+      event->SetHandled();
+      return;
     }
   }
 
-  return ImageButton::OnGestureEvent(event);
+  ImageButton::OnGestureEvent(event);
 }
 
 void FrameMaximizeButton::ProcessStartEvent(const ui::LocatedEvent& event) {
diff --git a/ash/wm/workspace/frame_maximize_button.h b/ash/wm/workspace/frame_maximize_button.h
index 6179deb..2e76bbb 100644
--- a/ash/wm/workspace/frame_maximize_button.h
+++ b/ash/wm/workspace/frame_maximize_button.h
@@ -66,7 +66,7 @@ class ASH_EXPORT FrameMaximizeButton : public views::ImageButton,
   virtual void OnMouseCaptureLost() OVERRIDE;
 
   // ui::EventHandler overrides:
-  virtual ui::EventResult OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
+  virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
 
   // Unit test overwrite: Change the UI delay used for the bubble show up.
   void set_bubble_appearance_delay_ms(int bubble_appearance_delay_ms) {
diff --git a/ash/wm/workspace/workspace_event_handler.cc b/ash/wm/workspace/workspace_event_handler.cc
index 75626ff..929d09c 100644
--- a/ash/wm/workspace/workspace_event_handler.cc
+++ b/ash/wm/workspace/workspace_event_handler.cc
@@ -106,15 +106,16 @@ ui::EventResult WorkspaceEventHandler::OnMouseEvent(ui::MouseEvent* event) {
   return ToplevelWindowEventHandler::OnMouseEvent(event);
 }
 
-ui::EventResult WorkspaceEventHandler::OnGestureEvent(ui::GestureEvent* event) {
+void WorkspaceEventHandler::OnGestureEvent(ui::GestureEvent* event) {
   aura::Window* target = static_cast<aura::Window*>(event->target());
   if (event->type() == ui::ET_GESTURE_DOUBLE_TAP &&
       target->delegate()->GetNonClientComponent(event->location()) ==
       HTCAPTION) {
     ToggleMaximizedState(target);  // |this| may be destroyed from here.
-    return ui::ER_CONSUMED;
+    event->StopPropagation();
+    return;
   }
-  return ToplevelWindowEventHandler::OnGestureEvent(event);
+  ToplevelWindowEventHandler::OnGestureEvent(event);
 }
 
 void WorkspaceEventHandler::HandleVerticalResizeDoubleClick(
diff --git a/ash/wm/workspace/workspace_event_handler.h b/ash/wm/workspace/workspace_event_handler.h
index 62da0bd..66e10d0 100644
--- a/ash/wm/workspace/workspace_event_handler.h
+++ b/ash/wm/workspace/workspace_event_handler.h
@@ -24,7 +24,7 @@ class WorkspaceEventHandler : public ToplevelWindowEventHandler {
 
   // Overridden from ToplevelWindowEventHandler:
   virtual ui::EventResult OnMouseEvent(ui::MouseEvent* event) OVERRIDE;
-  virtual ui::EventResult OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
+  virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
 
  private:
   friend class WorkspaceEventHandlerTestHelper;