Force repaint holding space views when updating images.

Holding space views are failing to repaint when being updated async.

Bug: 1134284
Change-Id: I573e44f4256d11a437d5c7a239ed48553443787a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2443451
Commit-Queue: David Black <dmblack@google.com>
Commit-Queue: Alex Newcomer <newcomer@chromium.org>
Auto-Submit: David Black <dmblack@google.com>
Reviewed-by: Alex Newcomer <newcomer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#812892}

ash/system/holding_space/holding_space_item_chip_view.cc

@@ -56,6 +56,7 @@ void HoldingSpaceItemChipView::UpdateImage() {
   image_->SetImage(
       item()->image().image_skia(),
       gfx::Size(kHoldingSpaceChipIconSize, kHoldingSpaceChipIconSize));
+  SchedulePaint();
 }
 
 BEGIN_METADATA(HoldingSpaceItemChipView, HoldingSpaceItemView)

ash/system/holding_space/holding_space_item_screenshot_view.cc

@@ -51,6 +51,7 @@ HoldingSpaceItemScreenshotView::~HoldingSpaceItemScreenshotView() = default;
 
 void HoldingSpaceItemScreenshotView::UpdateImage() {
   image_->SetImage(item()->image().image_skia(), kHoldingSpaceScreenshotSize);
+  SchedulePaint();
 }
 
 BEGIN_METADATA(HoldingSpaceItemScreenshotView, HoldingSpaceItemView)