[splitter] Block hover and resize cursor effects when inactive

If the pointer is down anywhere in the app, hovering over the splitter
bar or its child button shows their :hover effect even though they are
not active and a resize-cursor as well.

Block their hover and resize-cursor effect if the splitter is inactive
(files-ng) so the splitter looks inert (aka non-interactive).

Bug: 1062902, 1002790
Change-Id: I3fa170ea27682f52cc49ffe5d57bd2038c17d0b9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2119463Reviewed-by: Alex Danilo <adanilo@chromium.org>
Commit-Queue: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#753146}

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

@@ -436,6 +436,10 @@ body.files-ng div.splitter .splitter-button {
   width: 32px;
 }
 
+html.pointer-active body.files-ng div.splitter:not(.splitter-active):hover {
+  cursor: default;
+}
+
 body.files-ng div.splitter.splitter-active .splitter-button:hover {
   --hover-bg-color: none;
 }
@@ -444,6 +448,11 @@ html.col-resize body.files-ng div.splitter:not(.splitter-active) .splitter-butto
   --hover-bg-color: none;
 }
 
+html.pointer-active body.files-ng div.splitter:not(.splitter-active) .splitter-button:not(:active):hover {
+  --hover-bg-color: none;
+  cursor: default;
+}
+
 body.files-ng div.splitter.splitter-active .splitter-button:not(:active) {
   background-color: rgba(var(--google-grey-300-rgb), 88%);
 }
@@ -465,6 +474,11 @@ html:not(.col-resize) body.files-ng div.splitter:not(.splitter-active) .splitter
   background-color: var(--google-grey-500);
 }
 
+html.pointer-active body.files-ng div.splitter:not(.splitter-active) .splitter-button:not(:active):hover .icon {
+  background-color: var(--google-grey-300);
+  cursor: default;
+}
+
 body.files-ng div.splitter.splitter-active .splitter-button .icon {
   background-color: var(--google-grey-500);
 }