[Material Refresh] Separator blend from 43% to 30% per comment in bug.

Bug: 859620
Change-Id: I57b73343549028053aa5833587e28782815971c9
Reviewed-on: https://chromium-review.googlesource.com/1125127Reviewed-by: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#572347}

chrome/browser/ui/views/frame/browser_non_client_frame_view.cc

@@ -104,7 +104,7 @@ SkColor BrowserNonClientFrameView::GetToolbarTopSeparatorColor() const {
 
 SkColor BrowserNonClientFrameView::GetTabSeparatorColor() const {
   DCHECK(MD::IsRefreshUi());
-  constexpr SkAlpha kTabSeparatorAlpha = 0x6E;  // 43%
+  constexpr SkAlpha kTabSeparatorAlpha = 0x4D;  // 30%
   const SkColor frame_color = GetFrameColor();
   const SkColor base_color =
       color_utils::BlendTowardOppositeLuma(frame_color, SK_AlphaOPAQUE);