MD History: Add responsive layout which hides the sidebar in thin windows

ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-input/iron-input.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-spinner/paper-spinner-lite.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">
 
 <dom-module id="cr-toolbar-search-field">
   <template>
     <style>
       :host {
         align-items: center;
         display: flex;
         height: 40px;
         transition: background-color 150ms cubic-bezier(0.4, 0, 0.2, 1),
-            width 150ms cubic-bezier(0.4, 0, 0.2, 1);
+            width 150ms cubic-bezier(0.4, 0, 0.2, 1),
+            left 150ms cubic-bezier(0.4, 0, 0.2, 1);
         width: 44px;
       }
 
       [hidden] {
         display: none !important;
       }
 
       paper-icon-button {
         height: 32px;
         margin: 6px;
+        min-width: 32px;
         padding: 6px;
         width: 32px;
       }
 
       #icon {
         --paper-icon-button-ink-color: white;
         transition: opacity 150ms;
       }
 
       #prompt {
@@ skipping 45 matching lines @@
         opacity: 0.6;
       }
 
       :host(:not([narrow]):not([showing-search])) #prompt {
         visibility: visible;
       }
 
       /* Any layout, search open. */
       :host([showing-search]) {
         width: 100%;
+        left: 0;
       }
 
       :host([showing-search][spinner-active]) #icon {
         opacity: 0;
       }
-
-      :host([narrow][showing-search]) #icon {
-        -webkit-margin-start: 18px;
-      }
     </style>
     <paper-spinner-lite
         active="[[isSpinnerShown_(spinnerActive, showingSearch)]]">
     </paper-spinner-lite>
     <paper-icon-button id="icon" icon="cr:search" title="[[label]]"
         tabindex$="[[computeIconTabIndex_(narrow)]]">
     </paper-icon-button>
     <paper-input-container on-search="onSearchTermSearch"
         on-keydown="onSearchTermKeydown" on-keypress="onSearchTermKeypress_"
         no-label-float>
       <label id="prompt" for="searchInput">[[label]]</label>
       <input is="iron-input" id="searchInput" type="search"
           on-blur="onInputBlur_" incremental></input>
     </paper-input-container>
     <paper-icon-button icon="cr:cancel" id="clearSearch"
         title="[[clearLabel]]" hidden$="[[!hasSearchText]]"
         on-tap="hideSearch_">
     </paper-icon-button>
   </template>
   <script src="cr_toolbar_search_field.js"></script>
 </dom-module>