Prefer FocusRings on all platforms

After r713254 there are hopefully no longer performance issues with
enabling FocusRings everywhere.

Bug: chromium:924232
Change-Id: I99cca2635f3d618d72b2371ce6a07eecea01ffee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1903611Reviewed-by: Wei Li <weili@chromium.org>
Commit-Queue: Peter Boström <pbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713896}

ui/views/style/platform_style.cc

@@ -49,7 +49,7 @@ const bool PlatformStyle::kTreeViewSelectionPaintsEntireRow = false;
 const bool PlatformStyle::kUseRipples = true;
 const bool PlatformStyle::kTextfieldScrollsToStartOnFocusChange = false;
 const bool PlatformStyle::kTextfieldUsesDragCursorWhenDraggable = true;
-const bool PlatformStyle::kPreferFocusRings = false;
+const bool PlatformStyle::kPreferFocusRings = true;
 const bool PlatformStyle::kInactiveWidgetControlsAppearDisabled = false;
 
 // static