[MD History] Add UMA stats for switching views and the CBD button.

chrome/browser/resources/md_history/synced_device_manager.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-list/iron-list.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-item/paper-item.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_shared_menu/cr_shared_menu.html">
 <link rel="import" href="chrome://history/lazy_render.html">
 <link rel="import" href="chrome://history/shared_style.html">
 <link rel="import" href="chrome://history/synced_device_card.html">
 
 <dom-module id="history-synced-device-manager">
@@ skipping 55 matching lines @@
         <history-synced-device-card device="[[syncedDevice.device]]"
             last-update-time="[[syncedDevice.lastUpdateTime]]"
             tabs="[[syncedDevice.tabs]]"
             separator-indexes="[[syncedDevice.separatorIndexes]]"
             search-term="[[searchTerm]]"
             session-tag="[[syncedDevice.tag]]">
         </history-synced-device-card>
       </template>
     </div>
     <div id="no-synced-tabs" class="centered-message"
-        hidden="[[!showNoSyncedMessage(signInState_, syncedDevices_.length,
+        hidden="[[!showNoSyncedMessage(signInState, syncedDevices_.length,
                                        guestSession_)]]">
       [[noSyncedTabsMessage(fetchingSyncedTabs_)]]
     </div>
     <div id="sign-in-guide"
-        hidden="[[!showSignInGuide(signInState_, guestSession_)]]">
+        hidden="[[!showSignInGuide(signInState, guestSession_)]]">
       <div id="illustration"></div>
       <div id="sign-in-promo">$i18n{signInPromo}</div>
       <div id="sign-in-promo-desc">$i18n{signInPromoDesc}</div>
       <paper-button id="sign-in-button" on-tap="onSignInTap_">
         $i18n{signInButton}
       </paper-button>
     </div>
 
     <template is="history-lazy-render" id="menu">
       <cr-shared-menu>
         <paper-item class="menu-item" on-tap="onOpenAllTap_">
           $i18n{openAll}
         </paper-item>
         <paper-item class="menu-item" on-tap="onDeleteSessionTap_">
           $i18n{deleteSession}
         </paper-item>
       </cr-shared-menu>
     </template>
   </template>
   <script src="chrome://history/synced_device_manager.js"></script>
 </dom-module>