Fix classic inkdrop highlight for shelf app selection.

Dark/Classic shelf use light inkdrop highlights.

Bug: 1144136
Change-Id: I5690f73458c623fc82e7f891bfb3bdda963cb386
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2515200Reviewed-by: Min Chen <minch@chromium.org>
Reviewed-by: Yulun Wu <yulunwu@chromium.org>
Commit-Queue: Yulun Wu <yulunwu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825098}

ash/style/default_color_constants.h

@@ -23,7 +23,7 @@ constexpr SkColor kLoginButtonBackgroundBaseColor =
     SkColorSetA(SK_ColorWHITE, 26);
 
 // Colors for shelf.
-constexpr SkColor kDefaultShelfInkDropColor = SK_ColorBLACK;
+constexpr SkColor kDefaultShelfInkDropColor = SK_ColorWHITE;
 constexpr float kDefaultShelfInkDropOpacity = 0.2f;
 constexpr SkColor kShelfButtonColor = SK_ColorWHITE;
 constexpr SkColor kIndicatorColorActive = SK_ColorWHITE;