MD Settings: mouse movements should focus cr-action-menu items

ui/webui/resources/cr_elements/cr_action_menu/cr_action_menu.js

Index: ui/webui/resources/cr_elements/cr_action_menu/cr_action_menu.js
diff --git a/ui/webui/resources/cr_elements/cr_action_menu/cr_action_menu.js b/ui/webui/resources/cr_elements/cr_action_menu/cr_action_menu.js
index 9f58dc4f6cd9079f59c2ee05364b0f1f5aef5e46..3ed96d1f8ea38a2839230611509d78edaabc1016 100644
--- a/ui/webui/resources/cr_elements/cr_action_menu/cr_action_menu.js
+++ b/ui/webui/resources/cr_elements/cr_action_menu/cr_action_menu.js
@@ -32,6 +32,7 @@ Polymer({
 
   listeners: {
     'keydown': 'onKeyDown_',
+    'mousemove': 'onMouseMove_',
     'tap': 'onTap_',
   },
 
@@ -83,6 +84,27 @@ Polymer({
     e.preventDefault();
   },
 
+  debounceFlusher_: null,
+

[Dan Beam, 2017/04/04 22:32:00]

jsdoc here (@private, @param)

[scottchen, 2017/04/04 23:07:27]

Done.

+  onMouseMove_: function(e) {
+    var target = e.target;
+
+    if(!this.debounceFlusher_) {

[Dan Beam, 2017/04/04 22:32:00]

please use `git cl format --js` and/or stop forgetting spaces before braces or
parens

[scottchen, 2017/04/04 23:07:27]

I've formatted in the latest patch before you commented. Sorry, I just added you
as a reviewer early on because I wanted you to check out the debounce, wasn't
quite done with the CL yet with formatting/adding tests. 

Next time I'll just send you the link via chat and not click publish.

+      this.debounceFlusher_ = setTimeout(function(){
+        this.flushDebouncer('cr-action-menu-mousemove');
+        this.debounceFlusher_ = null;
+      }.bind(this), 10);
+    }
+
+    this.debounce('cr-action-menu-mousemove', function(){

[Dan Beam, 2017/04/04 22:32:00]

i don't understand why you need this debounce nor what you're doing

[scottchen, 2017/04/04 23:07:27]

mousemove fires a lot, so I was trying to make the code inside run less times.
Seems not worth based on offline discussion, removing.

+      if(target.classList.contains('dropdown-item') && 
+          target != document.activeElement)

[Dan Beam, 2017/04/04 22:32:00]

curlies for this if/else

[scottchen, 2017/04/04 23:07:27]

Done.

+        target.focus();
+      else
+        this.focus();  // Blur option focus but keep up/down button working.
+    }.bind(this), 10);
+  },
+
   /**
    * @param {number} step -1 for getting previous option (up), 1 for getting
    *     next option (down).