Increase opacity of holding space item selection overlay.

Previously was 24%. Spec calls for 30%.

Bug: 1169320
Change-Id: I793520a07de8fb706e7d5a73ceff0d20e05ebcd5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2643360Reviewed-by: Toni Baržić <tbarzic@chromium.org>
Commit-Queue: David Black <dmblack@google.com>
Cr-Commit-Position: refs/heads/master@{#846222}

ash/public/cpp/holding_space/holding_space_constants.h

@@ -26,7 +26,7 @@ constexpr int kHoldingSpaceFocusInsets = -4;
 constexpr int kHoldingSpaceIconSize = 20;
 constexpr gfx::Size kHoldingSpaceScreenCaptureSize(104, 80);
 constexpr int kHoldingSpaceSectionChildSpacing = 16;
-constexpr float kHoldingSpaceSelectedOverlayOpacity = 0.24f;
+constexpr float kHoldingSpaceSelectedOverlayOpacity = 0.3f;
 constexpr int kHoldingSpaceTrayIconMaxVisiblePreviews = 3;
 constexpr int kHoldingSpaceTrayIconDefaultPreviewSize = 32;
 constexpr int kHoldingSpaceTrayIconSmallPreviewSize = 28;