Implement account switcher as action-bar navigation spinner.

remoting/resources/strings.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!--User-facing strings for the Android app-->
 <!--TODO(solb) Merge in with localized strings-->
 <resources>
     <!--Instructional blurbs-->
     <string name="inst_host_list">My computers:</string>
     <string name="inst_empty_list">There are no computers to display</string>
 
     <!--Dialog box messages-->
     <string name="progress_title">Starting remote desktop session</string>
     <string name="pin_entry_title">Authenticate to host</string>
     <string name="pin_entry_message">Enter the host\'s PIN</string>
     <string name="pin_entry_pair">Don\'t ask in the future</string>
     <string name="pin_entry_connect">Connect</string>
     <string name="pin_entry_cancel">Cancel</string>
 
     <!--Action bar buttons-->
     <string name="actionbar_directoryrefresh">Refresh</string>
-    <string name="actionbar_accountswitcher">Accounts</string>
     <string name="actionbar_disconnect">Disconnect</string>
     <string name="actionbar_hide">Hide</string>
     <string name="actionbar_keyboard">Keyboard</string>
     <string name="actionbar_send_ctrl_alt_del">Send Ctrl-Alt-Del</string>
 
     <!--Informative messages-->
     <string name="msg_pin_canceled">No PIN was provided, so the connection attempt was canceled</string>
     <string name="msg_pin_entered">Attempting to authenticate to specified host with provided PIN</string>
 
     <!--Error messages-->
@@ skipping 24 matching lines @@
         <item>Host rejected connection</item>
         <item>Host using incompatible protocol</item>
         <item>Host rejected authentication</item>
         <item>Unable to establish data channel</item>
         <item>Bad signal</item>
         <item>Signal timed out</item>
         <item>Host received too many bad PINs</item>
         <item>Unknown error</item>
     </string-array>
 </resources>