Reset transforms on app list content views when the drag starts

Updates UpdateYPositionAndOpacity::UpdateYPositionAndOpacity to reset
transforms for views whose transform might have been changed in
ContentsView::AnimateToViewState(). This will ensure that the views are
positioned appropriatelly, and prevent them from animating as app list
view drag starts.

BUG=1042740

Change-Id: I1227a8ae52098d28331075ff1c681a6d16276137
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2005377
Commit-Queue: Toni Baržić <tbarzic@chromium.org>
Commit-Queue: Alex Newcomer <newcomer@chromium.org>
Reviewed-by: Alex Newcomer <newcomer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732563}

ash/app_list/views/apps_container_view.cc

@@ -260,6 +260,14 @@ void AppsContainerView::UpdateYPositionAndOpacity(float progress,
                         chip_grid_y_distance_);
   page_switcher_->SetY(suggestion_chip_container_view_->y() +
                        chip_grid_y_distance_);
+
+  // If app list is in drag, reset transforms that might started animating in
+  // AnimateYPosition().
+  if (app_list_view->is_in_drag()) {
+    suggestion_chip_container_view_->layer()->SetTransform(gfx::Transform());
+    apps_grid_view_->layer()->SetTransform(gfx::Transform());
+    page_switcher_->layer()->SetTransform(gfx::Transform());
+  }
 }
 
 void AppsContainerView::OnTabletModeChanged(bool started) {

ash/app_list/views/contents_view.cc

@@ -794,6 +794,15 @@ void ContentsView::UpdateYPositionAndOpacity() {
                                    search_box_bounds);
   }
 
+  // If in drag, reset the transforms that might have been set in
+  // AnimateToViewState().
+  if (app_list_view_->is_in_drag()) {
+    search_box->layer()->SetTransform(gfx::Transform());
+    expand_arrow_view_->layer()->SetTransform(gfx::Transform());
+    for (AppListPage* page : app_list_pages_)
+      page->layer()->SetTransform(gfx::Transform());
+  }
+
   if (app_list_features::IsScalableAppListEnabled() ||
       current_state == AppListState::kStateApps) {
     // Layout the apps container at the position where it would be with apps