[MD settings] move the subpage search underline up

chrome/browser/resources/settings/settings_page/settings_subpage_search.html

 <link rel="import" href="chrome://resources/cr_elements/cr_search_field/cr_search_field_behavior.html">
 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-input/paper-input-container.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-input/paper-input.html">
 
 <dom-module id="settings-subpage-search">
   <template>
     <style>
       :host {
+        --subpage-search-underline: {

[stevenjb, 2016/09/08 16:36:06]

nit: Would it be more clear if we named these something something like
--paper-input-container-underline--search so that it could be in the same :host
block? I don't really have a strong opinion, just a thought.

[dschuyler, 2016/09/08 16:57:44]

I wondered about something similar. My reasoning is that
it's more clear to 'know' that --paper-* refers to polymer
paper elements.

I'm wondering about excluding --foo- vars from the 
alphabetical requirement. I'll start a doc or separate thread
about it.

+          margin-bottom: -2px;
+          margin-top: -2px;
+        }
+      }
+
+      :host {
+        --paper-input-container-underline: var(--subpage-search-underline);
+        --paper-input-container-underline-focus:
+            var(--subpage-search-underline);
+        --paper-input-container-underline-disabled:
+            var(--subpage-search-underline);
         --paper-input-suffix: {
           /* Required to align the icon in |clearSearch| vertically. */
           line-height: 0;
         }
       }
 
       paper-icon-button {
         /* A 16px icon that fits on the input line. */
         height: 24px;
         padding: 4px;
@@ skipping 33 matching lines @@
       <input is="iron-input" id="searchInput" type="search"
           aria-labelledby="prompt" incremental>
       </input>
       <paper-icon-button suffix icon="cr:cancel" id="clearSearch"
           on-tap="onTapClear_" title="[[clearLabel]]" hidden$="[[!lastValue_]]">
       </paper-icon-button>
     </paper-input-container>
   </template>
   <script src="settings_subpage_search.js"></script>
 </dom-module>