MD History: Added a clear browsing data button

chrome/browser/resources/md_history/history_toolbar.html

 <link rel="import" href="chrome://resources/polymer/v1_0/polymer/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/cr_elements/cr_search_field/cr_search_field.html">
 
 <dom-module id="history-toolbar">
   <template>
 
     <style>
       :host {
         @apply(--layout-center);
         @apply(--layout-horizontal);
         background: #3f5566;
         color: #fff;
         height: 56px;
         transition: background-color 150ms;
         width: 100%;
       }
 
       :host([items-selected_]) {
         background: rgb(68, 136, 255);
       }
 
       h1 {
         @apply(--layout-flex);
+        @apply(--layout-horizontal);
         font-size: 16px;
         font-weight: 400;
         padding-left: 24px;
       }
 
-      #items {
+      .items {
+        @apply(--layout-horizontal);
         @apply(--layout-center);
-        @apply(--layout-horizontal);
         margin: 0 auto;
         max-width: 960px;
         width: 100%;
       }
 
       #number-selected {
         @apply(--layout-flex);
       }
 
       paper-icon-button {
         height: 36px;
         margin: 0 24px 0 2px;
         min-width: 36px;
         width: 36px;
       }
+
+      #clear-browsing-data {
+        flex: 1 1 960px;

[calamity, 2016/02/05 00:43:37]

We should convert this 960px value into a variable in a shared style sheet that
we can use across elements. Or a mixin. Either way, I don't want to have to
change this value in 5 different places when UX wants the card thinner.
(Follow-up patch)

+        max-width: 960px;
+        pointer-events: auto;
+      }
+
+      :host([items-selected_]) #clear-browsing-data {
+        display: none;
+      }
+
+      #button-container  {
+        @apply(--layout-horizontal);
+        @apply(--layout-center);
+        height: inherit;
+        left: 0;
+        pointer-events: none;
+        position: absolute;
+        top: 0;
+        width: 100%;
+      }
+
+      #toolbar-container {
+        @apply(--layout-horizontal);
+        @apply(--layout-center);
+        width: 100%;
+      }
+
+      #front-padding {
+        flex: 1 1 0;
+        min-width: 100px;
+      }
+
+      #back-padding {
+        flex: 1 1 0;
+        pointer-events: none;
+      }
     </style>
+    <div id="toolbar-container">
+      <template is="dom-if" if="{{!itemsSelected_}}">
+        <h1 i18n-content="title" id="title"></h1>
+        <cr-search-field id="search-input"
+            i18n-values="label:search;clear-label:clearSearch"></cr-search-field>

[calamity, 2016/02/05 00:43:37]

nit: Wrap.

+      </template>
 
-    <template is="dom-if" if="{{!itemsSelected_}}">
-      <h1 i18n-content="title" id="title"></h1>
-      <cr-search-field id="search-input"
-          i18n-values="label:search;clear-label:clearSearch"></cr-search-field>
-    </template>
-
-    <template is="dom-if" if="{{itemsSelected_}}">
-      <div id="items">
-        <paper-icon-button icon="clear" id="cancel-icon-button"
-            on-tap="onClearSelectionTap_">
-        </paper-icon-button>
-        <!-- TODO: change "selected" and number to an i18n (or equivalent)
-              string -->
-        <div id="number-selected">{{count}} selected</div>
-        <paper-button id="cancel-button" on-tap="onClearSelectionTap_">
-          CANCEL
+      <template is="dom-if" if="{{itemsSelected_}}">
+        <div class="items">
+          <paper-icon-button icon="clear" id="cancel-icon-button"
+              on-tap="onClearSelectionTap_">
+          </paper-icon-button>
+          <!-- TODO: change "selected" and number to an i18n (or equivalent)
+                string -->
+          <div id="number-selected">{{count}} selected</div>
+          <paper-button id="cancel-button" on-tap="onClearSelectionTap_">
+            CANCEL
+          </paper-button>
+          <paper-button id="delete-button">DELETE</paper-button>
+        </div>
+      </template>
+    </div>
+    <div id="button-container">
+      <div id="front-padding"></div>
+      <div id="clear-browsing-data">
+        <paper-button on-tap="clearBrowsingData" i18n-content="clearBrowsingData">

[tsergeant, 2016/02/04 02:49:02]

Rename this event to the standard format:

onClearBrowsingDataTap_

(Also, wrap to 80 characters)

[yingran, 2016/02/04 23:29:43]

Done.

         </paper-button>
-        <paper-button id="delete-button">DELETE</paper-button>
       </div>
-    </template>
-
+      <div id="back-padding"></div>
+    </div>
   </template>
   <script src="chrome://history/history_toolbar.js"></script>
 </dom-module>