Tablet WM : Swiping on system tray bubble.

ash/system/tray/system_tray.h

Index: ash/system/tray/system_tray.h
diff --git a/ash/system/tray/system_tray.h b/ash/system/tray/system_tray.h
index fa16c53f74067aaee8e1eacaccff91add8d1d17d..dd9790d36806e082e03787c583f10971ec8b9c95 100644
--- a/ash/system/tray/system_tray.h
+++ b/ash/system/tray/system_tray.h
@@ -142,6 +142,11 @@ class ASH_EXPORT SystemTray : public TrayBackgroundView,
   // Activates the system tray bubble.
   void ActivateBubble();
 
+  // ui::EventHandler:
+  void OnGestureEvent(ui::GestureEvent* event) override;
+
+  gfx::Rect GetWorkAreaBoundsInScreen() const;
+
  private:
   friend class SystemTrayTestApi;
   class ActivationObserver;
@@ -193,6 +198,36 @@ class ASH_EXPORT SystemTray : public TrayBackgroundView,
   // Overridden from ActionableView.
   bool PerformAction(const ui::Event& event) override;
 
+  // Gesture related functions:
+  bool ProcessGestureEvent(const ui::GestureEvent& event);
+  bool StartGestureDrag(const ui::GestureEvent& gesture);
+  void UpdateGestureDrag(const ui::GestureEvent& gesture);
+  void CompleteGestureDrag(const ui::GestureEvent& gesture);
+
+  // Returns true if swiping down triggered on the system tray area on the
+  // shelf.
+  bool IsDraggingDownOnShelf(const ui::GestureEvent& gesture);
+
+  // Update the bounds of the system tray bubble according to the location of
+  // the gesture drag.
+  void UpdateBoundsOnDragging(const ui::GestureEvent& gesture);
+
+  // For SCROLL event, open the system tray bubble if the drag amount is larger
+  // than one third of the  height of the bubble. Otherwise, close it. For FLING
+  // event. If the fling velocity is larger than 100.0 dips/sec, open or close
+  // the bubble depends on the fling direction. Otherwise, the rule is the same
+  // as SCROLL event.
+  bool ShouldShowSystemBubbleForDragging(const ui::GestureEvent& gesture);

[tdanderson, 2017/06/20 22:42:28]

With the current implementation, once the system menu is already open, you
cannot close it by swiping (you said you would address that in a future CL). So
as-is, I find it a bit misleading to use the term "close" here. How about the
following suggestion for documentation and a function name which I think makes
this a bit clearer:

// Returns true if the system bubble should be shown (i.e.,
// animated upward to be made fully visible) after a
// sequence of scroll events terminated by |sequence_end|. Otherwise
// return false, indicating that the partially-visible system bubble
// should be animated downward and made fully hidden.
bool ShouldShowSystemBubbleAfterScrollSequence(const ui::GestureEvent&
sequence_end);

I have made suggestions for inline documentation in the .cc.

[minch1, 2017/06/22 17:42:11]

Done.

+
+  // Shelf the system tray is in.
+  Shelf* const shelf_;
+
+  // The original bounds of the system tray bubble.
+  gfx::Rect system_tray_bubble_bounds_;
+
+  // Tracks the amount of the drag.
+  float gesture_drag_amount_ = 0.f;
+
   // The web notification tray view that appears adjacent to this view.
   WebNotificationTray* web_notification_tray_ = nullptr;