[MD settings] use arrow-forward to switch direction in rtl

chrome/browser/resources/settings/settings_shared_css.html

 <link rel="import" href="chrome://resources/cr_elements/shared_style_css.html">
 <link rel="import" href="/settings_vars_css.html">
 
 <!-- Common styles for Material Design settings. -->
 <dom-module id="settings-shared">
   <template>
     <style include="cr-shared-style">
       button[is='paper-icon-button-light'] {
         --paper-icon-button-light-ripple: {
           /* Center the ripple on the icon button. */
-          height: 36px;
+          height: var(--settings-icon-ripple-size);
           left: -8px;
           top: -8px;
-          width: 36px;
+          width: var(--settings-icon-ripple-size);
         };
         -webkit-margin-start: 16px;
         background-size: cover;
         flex-shrink: 0;
-        height: 20px;
-        width: 20px;
+        height: var(--settings-icon-size);
+        width: var(--settings-icon-size);
       }
 
-      [actionable] button[is="paper-icon-button-light"].icon-arrow-right {
+      :host-context([dir=rtl]) button[is='paper-icon-button-light'] {
+        --paper-icon-button-light-ripple: {
+          /* Center the ripple on the icon button. */
+          height: var(--settings-icon-ripple-size);
+          right: -8px;
+          top: -8px;
+          width: var(--settings-icon-ripple-size);
+        };
+      }
+
+      [actionable] button[is="paper-icon-button-light"].icon-arrow-forward {
         background-image: url(images/arrow_right.svg);
       }
 
+      :host-context([dir=rtl]) [actionable] button[is="paper-icon-button-light"].icon-arrow-forward {

[Dan Beam, 2016/10/03 22:04:54]

wrap

[dschuyler, 2016/10/03 22:22:41]

Removed.

+        background-image: url(images/arrow_left.svg);

[Dan Beam, 2016/10/03 22:04:54]

why can't we just transform?

[dschuyler, 2016/10/03 22:22:41]

We can. I had trouble with the -webkit-margin-start.
I've made patch#2 that shows a working version 
without the arrow_left.svg. It has some extra comments
talking about the workaround for the margin.

+      }
+
       [actionable] button[is="paper-icon-button-light"].icon-external {
         background-image: url(images/open_in_new.svg);
       }
 
       /* Use <h2> as the "sub-header" mentioned in the UX design docs. */
       h2 {
         align-items: center;
         align-self: flex-start;
         color: var(--paper-grey-600);
         display: flex;
@@ skipping 387 matching lines @@
       /* Turns the arrow direction downwards, when the bubble is placed above
        * the anchor element */
       .search-bubble-innards.above::after {
         -webkit-transform: rotate(-135deg);
         bottom: -5px;
         top: auto;
       }
     </style>
   </template>
 </dom-module>