Forward events to the apps grid view if they are in the same y-region

This allows for scrolling on the very edge to paginate the apps grid first,
before closing the launcher. By limiting the Y-region, you can still close
the launcher with a drag from the top.

Bug: 869642
Change-Id: Ice9759a2e1dd0c3beb6019a00b570bba37e2a7a6
Reviewed-on: https://chromium-review.googlesource.com/1175454Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Weidong Guo <weidongg@chromium.org>
Commit-Queue: Kevin Strohbehn <ginko@google.com>
Cr-Commit-Position: refs/heads/master@{#584271}

ash/app_list/views/apps_container_view.cc

@@ -316,6 +316,31 @@ const char* AppsContainerView::GetClassName() const {
   return "AppsContainerView";
 }
 
+void AppsContainerView::OnGestureEvent(ui::GestureEvent* event) {
+  // Will forward events to |apps_grid_view_| if they occur in the same y-region
+  if (event->type() == ui::ET_GESTURE_SCROLL_BEGIN &&
+      event->location().y() <= apps_grid_view_->bounds().y()) {
+    return;
+  }
+
+  // If a folder is currently opening or closing, we should ignore the event.
+  // This is here until the animation for pagination while closing folders is
+  // fixed: https://crbug.com/875133
+  if (app_list_folder_view_->IsAnimationRunning()) {
+    event->SetHandled();
+    return;
+  }
+
+  // Temporary event for use by |apps_grid_view_|
+  ui::GestureEvent grid_event(*event);
+  ConvertEventToTarget(apps_grid_view_, &grid_event);
+  apps_grid_view_->OnGestureEvent(&grid_event);
+
+  // If the temporary event was handled, we don't want to handle it again.
+  if (grid_event.handled())
+    event->SetHandled();
+}
+
 void AppsContainerView::OnWillBeHidden() {
   if (show_state_ == SHOW_APPS || show_state_ == SHOW_ITEM_REPARENT)
     apps_grid_view_->EndDrag(true);

ash/app_list/views/apps_container_view.h

@@ -74,6 +74,7 @@ class APP_LIST_EXPORT AppsContainerView : public HorizontalPage {
   void Layout() override;
   bool OnKeyPressed(const ui::KeyEvent& event) override;
   const char* GetClassName() const override;
+  void OnGestureEvent(ui::GestureEvent* event) override;
 
   // HorizontalPage overrides:
   void OnWillBeHidden() override;

ash/app_list/views/folder_background_view.cc

@@ -19,8 +19,10 @@ bool FolderBackgroundView::OnMousePressed(const ui::MouseEvent& event) {
 }
 
 void FolderBackgroundView::OnGestureEvent(ui::GestureEvent* event) {
-  if (event->type() != ui::ET_GESTURE_TAP)
-    return;
+  // A fix for the current folder close animation should be implemented to allow
+  // for a folder to close while pages are changing. Until this, we should
+  // always close the folder before movement.
+  // https://crbug.com/875133
   HandleClickOrTap();
   event->SetHandled();
 }