Change ink-color on action bar cr-button(s)

Bug: 992823
Change-Id: I7e112d7e113914b0ca8088bbe2843715ec12a2c5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2054469
Commit-Queue: Noel Gordon <noel@chromium.org>
Reviewed-by: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#741377}

ui/file_manager/file_manager/foreground/css/file_manager.css

@@ -470,7 +470,7 @@ body[type='open-multi-file'].check-select .dialog-header {
 
 .dialog-header.files-ng cr-button {
   --hover-bg-color: rgba(0, 0, 0, 4%);
-  --ink-color: var(--google-grey-700);
+  --ink-color: rgba(0, 0, 0, 88%);
   --text-color: currentColor;
   border: 1px solid transparent;
   border-radius: 18px;