Add animation when swiping app list from shelf.

Swiping up from shelf to open app list is only for tablet currently.
So set state as FULLSCREEN_ALL_APPS directly to add the animation.
Otherwise, the app list will just snap to the top of the screen.

Bug: None
Change-Id: I281ae53700294221b0c96c9a2aa1d4c66822f2bf
Reviewed-on: https://chromium-review.googlesource.com/598740Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: min c <minch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491765}

ui/app_list/views/app_list_view.cc

@@ -960,9 +960,13 @@ void AppListView::SetStateFromSearchBoxView(bool search_box_is_empty) {
 void AppListView::UpdateYPositionAndOpacity(int y_position_in_screen,
                                             float background_opacity,
                                             bool is_end_gesture) {
-  gfx::Rect new_widget_bounds = fullscreen_widget_->GetWindowBoundsInScreen();
-  new_widget_bounds.set_y(std::max(y_position_in_screen, 0));
-  fullscreen_widget_->SetBounds(new_widget_bounds);
+  if (is_end_gesture) {
+    SetState(FULLSCREEN_ALL_APPS);
+  } else {
+    gfx::Rect new_widget_bounds = fullscreen_widget_->GetWindowBoundsInScreen();
+    new_widget_bounds.set_y(std::max(y_position_in_screen, 0));
+    fullscreen_widget_->SetBounds(new_widget_bounds);
+  }
 
   UpdateOpacity(background_opacity, is_end_gesture);
 }