splitview: Correct the opacity of the split view highlight in overview.

In overview, the split view drag indicator always has an opacity of 18%,
whereas the specification calls for 30% when indicating where to drag a
window, and 18% when serving as a preview of snapped window bounds:
https://mccanny.users.x20web.corp.google.com/www/splitscreen-motion/index.html#indicator-expand

Test: manual
Bug: 808283
Change-Id: I4cbf1230f34d3b90389c60d8fc909298b8b9d386
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1500912
Commit-Queue: Avery Musbach <amusbach@chromium.org>
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#637549}

ash/wm/splitview/split_view_utils.cc

@@ -58,7 +58,6 @@ void GetAnimationValuesForType(
     case SPLITVIEW_ANIMATION_HIGHLIGHT_FADE_IN:
     case SPLITVIEW_ANIMATION_HIGHLIGHT_FADE_OUT:
     case SPLITVIEW_ANIMATION_PREVIEW_AREA_FADE_IN:
-    case SPLITVIEW_ANIMATION_PREVIEW_AREA_FADE_OUT:
     case SPLITVIEW_ANIMATION_OVERVIEW_ITEM_FADE_IN:
     case SPLITVIEW_ANIMATION_OVERVIEW_ITEM_FADE_OUT:
     case SPLITVIEW_ANIMATION_TEXT_FADE_IN_WITH_HIGHLIGHT:
@@ -67,7 +66,6 @@ void GetAnimationValuesForType(
       *out_duration = kHighlightsFadeInOutMs;
       *out_tween_type = gfx::Tween::FAST_OUT_SLOW_IN;
       return;
-    case SPLITVIEW_ANIMATION_OTHER_HIGHLIGHT_FADE_IN:
     case SPLITVIEW_ANIMATION_OTHER_HIGHLIGHT_SLIDE_IN:
       *out_duration = kOtherFadeInOutMs;
       *out_tween_type = gfx::Tween::LINEAR_OUT_SLOW_IN;
@@ -132,12 +130,10 @@ void DoSplitviewOpacityAnimation(ui::Layer* layer,
     case SPLITVIEW_ANIMATION_TEXT_FADE_OUT_WITH_HIGHLIGHT:
       target_opacity = 0.f;
       break;
-    case SPLITVIEW_ANIMATION_HIGHLIGHT_FADE_IN:
-    case SPLITVIEW_ANIMATION_OTHER_HIGHLIGHT_FADE_IN:
     case SPLITVIEW_ANIMATION_PREVIEW_AREA_FADE_IN:
       target_opacity = kPreviewAreaHighlightOpacity;
       break;
-    case SPLITVIEW_ANIMATION_PREVIEW_AREA_FADE_OUT:
+    case SPLITVIEW_ANIMATION_HIGHLIGHT_FADE_IN:
       target_opacity = kHighlightOpacity;
       break;
     case SPLITVIEW_ANIMATION_OVERVIEW_ITEM_FADE_IN:

ash/wm/splitview/split_view_utils.h

@@ -27,16 +27,14 @@ enum SplitviewAnimationType {
   // to drag a selector item.
   SPLITVIEW_ANIMATION_HIGHLIGHT_FADE_IN,
   SPLITVIEW_ANIMATION_HIGHLIGHT_FADE_OUT,
-  // Used to fade in and out the other highlight. There are normally two
-  // highlights, one on each side. When entering a state with a preview
-  // highlight, one highlight is the preview highlight, and the other highlight
-  // is the other highlight.
-  SPLITVIEW_ANIMATION_OTHER_HIGHLIGHT_FADE_IN,
+  // Used to fade out the other highlight. There are normally two highlights,
+  // one on each side. When entering a state with a preview highlight, one
+  // highlight is the preview highlight, and the other highlight is the other
+  // highlight.
   SPLITVIEW_ANIMATION_OTHER_HIGHLIGHT_FADE_OUT,
-  // Used to fade in and out the preview area highlight which indicate the
-  // bounds of the window that is about to get snapped.
+  // Used to fade in the preview area highlight which indicates the bounds of
+  // the window that is about to get snapped.
   SPLITVIEW_ANIMATION_PREVIEW_AREA_FADE_IN,
-  SPLITVIEW_ANIMATION_PREVIEW_AREA_FADE_OUT,
   // Used to fade in and out the label on the overview item which warns users
   // the item cannot be snapped. The label appears on the overview item after
   // another window has been snapped.