ash: Cleanup TrayBubbleView MouseWatcher and delegates

Cleanup TrayBubbleView's MouseWatcher comments.
Remove a TimeDelta that was being used incorrectly.
(controls the callback delay, not a mouse sampling rate)

Remove no-op delegate function overrides (default is no-op).
Remove a call to the no-op BubbleDialogDelegateView::OnGestureEvent.

Bug: None
Test: No tray bubble (volume/brightness) auto-close regressions.
Change-Id: I1bf3775b22a147f2d42557ff4a71dba153c5bb6c
Reviewed-on: https://chromium-review.googlesource.com/1241195Reviewed-by: James Cook <jamescook@chromium.org>
Commit-Queue: Michael Wasserman <msw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593662}

ash/system/ime_menu/ime_menu_tray.cc

@@ -492,13 +492,6 @@ void ImeMenuTray::OnIMEMenuActivationChanged(bool is_activated) {
     CloseBubble();
 }
 
-void ImeMenuTray::BubbleViewDestroyed() {
-}
-
-void ImeMenuTray::OnMouseEnteredView() {}
-
-void ImeMenuTray::OnMouseExitedView() {}
-
 base::string16 ImeMenuTray::GetAccessibleNameForBubble() {
   return l10n_util::GetStringUTF16(IDS_ASH_IME_MENU_ACCESSIBLE_NAME);
 }

ash/system/ime_menu/ime_menu_tray.h

@@ -65,9 +65,6 @@ class ASH_EXPORT ImeMenuTray : public TrayBackgroundView,
   void OnIMEMenuActivationChanged(bool is_activated) override;
 
   // TrayBubbleView::Delegate:
-  void BubbleViewDestroyed() override;
-  void OnMouseEnteredView() override;
-  void OnMouseExitedView() override;
   base::string16 GetAccessibleNameForBubble() override;
   bool ShouldEnableExtraKeyboardAccessibility() override;
   void HideBubble(const TrayBubbleView* bubble_view) override;

ash/system/message_center/notification_tray.cc

@@ -477,10 +477,6 @@ void NotificationTray::BubbleViewDestroyed() {
     message_center_bubble()->bubble()->BubbleViewDestroyed();
 }
 
-void NotificationTray::OnMouseEnteredView() {}
-
-void NotificationTray::OnMouseExitedView() {}
-
 base::string16 NotificationTray::GetAccessibleNameForBubble() {
   return GetAccessibleNameForTray();
 }

ash/system/message_center/notification_tray.h

@@ -73,8 +73,6 @@ class ASH_EXPORT NotificationTray
 
   // Overridden from TrayBubbleView::Delegate.
   void BubbleViewDestroyed() override;
-  void OnMouseEnteredView() override;
-  void OnMouseExitedView() override;
   base::string16 GetAccessibleNameForBubble() override;
   bool ShouldEnableExtraKeyboardAccessibility() override;
   void HideBubble(const TrayBubbleView* bubble_view) override;

ash/system/palette/palette_tray.cc

@@ -320,10 +320,6 @@ void PaletteTray::BubbleViewDestroyed() {
                              PaletteGroup::MODE) != PaletteToolId::NONE);
 }
 
-void PaletteTray::OnMouseEnteredView() {}
-
-void PaletteTray::OnMouseExitedView() {}
-
 base::string16 PaletteTray::GetAccessibleNameForBubble() {
   return GetAccessibleNameForTray();
 }

ash/system/palette/palette_tray.h

@@ -97,8 +97,6 @@ class ASH_EXPORT PaletteTray : public TrayBackgroundView,
 
   // TrayBubbleView::Delegate:
   void BubbleViewDestroyed() override;
-  void OnMouseEnteredView() override;
-  void OnMouseExitedView() override;
   base::string16 GetAccessibleNameForBubble() override;
   bool ShouldEnableExtraKeyboardAccessibility() override;
   void HideBubble(const TrayBubbleView* bubble_view) override;

ash/system/tray/tray_bubble_view.cc

@@ -42,10 +42,6 @@ namespace ash {
 
 namespace {
 
-// The sampling time for mouse position changes in ms - which is roughly a frame
-// time.
-const int kFrameTimeInMS = 30;
-
 BubbleBorder::Arrow GetArrowAlignment(
     TrayBubbleView::AnchorAlignment alignment) {
   if (alignment == TrayBubbleView::ANCHOR_ALIGNMENT_BOTTOM) {
@@ -401,32 +397,23 @@ int TrayBubbleView::GetHeightForWidth(int width) const {
 void TrayBubbleView::OnMouseEntered(const ui::MouseEvent& event) {
   mouse_watcher_.reset();
   if (delegate_ && !(event.flags() & ui::EF_IS_SYNTHESIZED)) {
-    // Coming here the user was actively moving the mouse over the bubble and
-    // we inform the delegate that we entered. This will prevent the bubble
-    // to auto close.
+    // The user actively moved the mouse over the bubble; inform the delegate.
     delegate_->OnMouseEnteredView();
     mouse_actively_entered_ = true;
   } else {
-    // Coming here the bubble got shown and the mouse was 'accidentally' over it
-    // which is not a reason to prevent the bubble to auto close. As such we
-    // do not call the delegate, but wait for the first mouse move within the
-    // bubble. The used MouseWatcher will notify use of a movement and call
-    // |MouseMovedOutOfHost|.
+    // The mouse was located over the bubble when it was first shown; use
+    // MouseWatcher to wait for user interaction before signaling the delegate.
     mouse_watcher_ = std::make_unique<views::MouseWatcher>(
         std::make_unique<MouseMoveDetectorHost>(), this);
-    // Set the mouse sampling frequency to roughly a frame time so that the user
-    // cannot see a lag.
-    mouse_watcher_->set_notify_on_exit_time(
-        base::TimeDelta::FromMilliseconds(kFrameTimeInMS));
+    mouse_watcher_->set_notify_on_exit_time(base::TimeDelta());
     mouse_watcher_->Start(GetWidget()->GetNativeWindow());
   }
 }
 
 void TrayBubbleView::OnMouseExited(const ui::MouseEvent& event) {
-  // If there was a mouse watcher waiting for mouse movements we disable it
-  // immediately since we now leave the bubble.
+  // Disable any MouseWatcher waiting for user interaction inside the bubble.
   mouse_watcher_.reset();
-  // Do not notify the delegate of an exit if we never told it that we entered.
+  // Only notify the delegate on exit if it was notified on enter.
   if (delegate_ && mouse_actively_entered_)
     delegate_->OnMouseExitedView();
 }
@@ -441,19 +428,14 @@ void TrayBubbleView::GetAccessibleNodeData(ui::AXNodeData* node_data) {
 void TrayBubbleView::OnGestureEvent(ui::GestureEvent* event) {
   if (delegate_)
     delegate_->ProcessGestureEventForBubble(event);
-
-  if (!event->handled())
-    BubbleDialogDelegateView::OnGestureEvent(event);
 }
 
 void TrayBubbleView::MouseMovedOutOfHost() {
-  // The mouse was accidentally over the bubble when it opened and the AutoClose
-  // logic was not activated. Now that the user did move the mouse we tell the
-  // delegate to disable AutoClose.
+  // The user moved the mouse that was over the bubble when it was first shown.
   if (delegate_)
     delegate_->OnMouseEnteredView();
   mouse_actively_entered_ = true;
-  mouse_watcher_->Stop();
+  mouse_watcher_.reset();
 }
 
 void TrayBubbleView::ChildPreferredSizeChanged(View* child) {