Site Settings Desktop: Implement protocol handler section.

chrome/browser/resources/settings/site_settings/protocol_handlers.html

+<link rel="import" href="chrome://resources/html/polymer.html">
+<link rel="import" href="chrome://resources/cr_elements/icons.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-toggle-button/paper-toggle-button.html">
+<link rel="import" href="chrome://resources/html/web_ui_listener_behavior.html">
+<link rel="import" href="/i18n_setup.html">
+<link rel="import" href="/settings_shared_css.html">
+<link rel="import" href="/site_settings/site_settings_behavior.html">
+<link rel="import" href="/site_settings/site_settings_prefs_browser_proxy.html">
+
+<dom-module id="protocol-handlers">
+  <template>
+    <style include="settings-shared">
+      :host {
+        display: block;
+      }
+
+      .protocol {
+        -webkit-margin-start: 20px;
+        margin-bottom: 15px;
+        margin-top: 15px;
+      }
+    </style>
+    <div class="settings-box first two-line">
+      <div class="start secondary">
+        [[computeHandlersDescription_(categoryEnabled)]]
+      </div>
+      <paper-toggle-button id="toggle" checked="{{categoryEnabled}}"
+          on-change="onToggleChange_"></paper-toggle-button>
+    </div>
+
+    <template is="dom-repeat" items="[[protocols]]" as="protocol">
+      <div class="protocol">[[protocol.protocol]]</div>
+
+      <div class="list-frame menu-content vertical-list">
+        <template is="dom-repeat" items="[[protocol.handlers]]">
+
+          <div class="list-item underscore">
+            <div class="middle" >
+              <div>[[item.host]]</div>
+              <div class="secondary"
+                  hidden$="[[!isDefault_(index, protocol.default_handler)]]">
+                $i18n{handlerIsDefault}
+              </div>
+            </div>
+
+            <paper-menu-button>

[michaelpg, 2016/07/10 17:54:43]

import paper-item, paper-menu, paper-menu-button

+              <paper-icon-button icon="cr:more-vert"
+                  class="dropdown-trigger">
+              </paper-icon-button>
+              <paper-menu id="actionMenu" class="dropdown-content"
+                  on-iron-activate="onActionMenuIronActivate_"
+                  attr-for-selected="menu-value">
+                <paper-item menu-value$="[[menuActions_.SET_DEFAULT]]"
+                    hidden$="[[isDefault_(index, protocol.default_handler)]]">
+                  $i18n{handlerSetDefault}
+                </paper-item>
+                <paper-item menu-value$="[[menuActions_.REMOVE]]">
+                  $i18n{handlerRemove}
+                </paper-item>
+              </paper-menu>
+            </paper-menu-button>
+          </div>
+
+        </template>
+      </div>
+    </template>
+  </template>
+  <script src="protocol_handlers.js"></script>
+</dom-module>