Introduce ash mojo interface for lock screen action handlers

chrome/browser/chromeos/chrome_browser_main_chromeos.h

Index: chrome/browser/chromeos/chrome_browser_main_chromeos.h
diff --git a/chrome/browser/chromeos/chrome_browser_main_chromeos.h b/chrome/browser/chromeos/chrome_browser_main_chromeos.h
index 3af4f64722203eaf1209e843ce45d80518a1af54..c74a338d2a8f2121c292676cad21399dd157c371 100644
--- a/chrome/browser/chromeos/chrome_browser_main_chromeos.h
+++ b/chrome/browser/chromeos/chrome_browser_main_chromeos.h
@@ -14,6 +14,10 @@
 #include "chrome/browser/memory/memory_kills_monitor.h"
 #include "chromeos/system/version_loader.h"
 
+namespace lock_screen_apps {
+class StateController;
+}
+
 namespace session_manager {
 class SessionManager;
 }
@@ -98,6 +102,9 @@ class ChromeBrowserMainPartsChromeos : public ChromeBrowserMainPartsLinux {
 
   std::unique_ptr<memory::MemoryKillsMonitor::Handle> memory_kills_monitor_;
 
+  std::unique_ptr<lock_screen_apps::StateController>
+      lock_screen_apps_state_controller_;
+
   DISALLOW_COPY_AND_ASSIGN(ChromeBrowserMainPartsChromeos);
 };