[scrollable shelf] Fix broken tests with flag enabled

Fix another two tests which are broken with the flag enabled:
(1) ShelfTooltipManagerTest.HideForEvents: The event generator fails
to reset the mouse button.
(2) ShelfWidgetTest.LauncherInitiallySized: It assumes that the
shelf widget's bounds are identical with the bounds of the shelf view.
However, it is incorrect with the scrollable shelf enabled.

Bug: 1002576
Change-Id: Ia573eef66a25b73e45b9b69e0e435320b2f07eca
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1808459
Commit-Queue: Andrew Xu <andrewxu@chromium.org>
Reviewed-by: Manu Cornet <manucornet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#697336}

ash/shelf/shelf_tooltip_manager_unittest.cc

@@ -183,6 +183,7 @@ TEST_F(ShelfTooltipManagerTest, HideForEvents) {
   generator->MoveMouseTo(shelf_bounds.CenterPoint());
   generator->PressLeftButton();
   EXPECT_FALSE(tooltip_manager_->IsVisible());
+  generator->ReleaseLeftButton();
 
   // Should hide for touch events in the shelf.
   ShowTooltipForFirstAppIcon();

ash/shelf/shelf_widget_unittest.cc

@@ -152,7 +152,7 @@ TEST_F(ShelfWidgetTest, LauncherInitiallySized) {
   const int nav_width =
       shelf_widget->navigation_widget()->GetWindowBoundsInScreen().width();
   const int hotseat_width =
-      GetPrimaryShelf()->GetShelfViewForTesting()->width();
+      shelf_widget->hotseat_widget()->GetWindowBoundsInScreen().width();
   const int margins = ShelfConfig::Get()->home_button_edge_spacing() +
                       ShelfConfig::Get()->app_icon_group_margin();
   EXPECT_EQ(status_width, total_width - nav_width - hotseat_width - margins);