MD History: Fix layout of expanded search box in small windows

chrome/browser/resources/md_history/history_toolbar.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/iron-flex-layout.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.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-spinner/paper-spinner.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_search_field/cr_search_field.html">
 <link rel="import" href="chrome://history/shared_style.html">
 
 <dom-module id="history-toolbar">
   <template>
@@ skipping 28 matching lines @@
 
       #left-content,
       #right-content {
         flex: 1 0 0;
       }
 
       :host([has-sidebar]) #left-content {
         flex: 1 0 var(--side-bar-width);
       }
 
-      #centered-buttons {
-        flex: 0 1 var(--card-max-width);
-        padding: 0 var(--card-padding-side);
+      #centered-content {
+        /** Padding-start gives space on one side, flex-basis gives space on the
+          other. */
+        -webkit-padding-start: var(--card-padding-side);
+        display: flex;
+        flex: 1 1 calc(var(--card-max-width) + var(--card-padding-side));
       }
 
       #right-content {
         @apply(--layout-center);
         @apply(--layout-horizontal);
         justify-content: flex-end;
       }
 
       #search-input {
         -webkit-padding-end: 20px;
@@ skipping 29 matching lines @@
 
       paper-button {
         pointer-events: auto;
       }
     </style>
     <div id="toolbar-container">
       <div id="main-content" hidden$="[[itemsSelected_]]">
         <div id="left-content">
           <h1 id="title">$i18n{title}</h1>
         </div>
-        <div id="centered-buttons">
+        <div id="centered-content">
           <paper-button on-tap="onClearBrowsingDataTap_"
               id="clear-browsing-data-button">
             $i18n{clearBrowsingData}
           </paper-button>
-        </div>
-        <div id="right-content">
-          <paper-spinner id="searching-spinner" active="[[searching]]">
-          </paper-spinner>
-          <cr-search-field id="search-input" label="$i18n{search}"
-              clear-label="$i18n{clearSearch}">
-          </cr-search-field>
+          <div id="right-content">
+            <paper-spinner id="searching-spinner" active="[[searching]]">
+            </paper-spinner>
+            <cr-search-field id="search-input" label="$i18n{search}"
+                clear-label="$i18n{clearSearch}">
+            </cr-search-field>
+          </div>
         </div>
       </div>
 
       <div id="overlay-wrapper" hidden$="[[!itemsSelected_]]">
         <div id="overlay-buttons">
           <paper-icon-button icon="clear" id="cancel-icon-button"
               on-tap="onClearSelectionTap_"></paper-icon-button>
           <div id="number-selected">[[numberOfItemsSelected_(count)]]</div>
           <paper-button id="cancel-button" on-tap="onClearSelectionTap_">
             $i18n{cancel}
           </paper-button>
           <paper-button id="delete-button" on-tap="onDeleteTap_">
             $i18n{delete}
           </paper-button>
         </div>
       </div>
     </div>
   </template>
   <script src="chrome://history/history_toolbar.js"></script>
 </dom-module>