cros: Move call js prefix out of ctor.

chrome/browser/ui/webui/chromeos/login/base_screen_handler.h

Index: chrome/browser/ui/webui/chromeos/login/base_screen_handler.h
diff --git a/chrome/browser/ui/webui/chromeos/login/base_screen_handler.h b/chrome/browser/ui/webui/chromeos/login/base_screen_handler.h
index 4c485f58039364806eff24c459b1552bc4f988f3..2e46198a8b3133fcf74b2347f5bbe7d6a0bf5daf 100644
--- a/chrome/browser/ui/webui/chromeos/login/base_screen_handler.h
+++ b/chrome/browser/ui/webui/chromeos/login/base_screen_handler.h
@@ -36,12 +36,7 @@ class OobeUI;
 class BaseScreenHandler : public content::WebUIMessageHandler,
                           public ModelViewChannel {
  public:
-  // C-tor used when JS screen prefix is not needed.
   BaseScreenHandler();
-
-  // C-tor used when JS screen prefix is needed.
-  explicit BaseScreenHandler(const std::string& js_screen_path);
-
   ~BaseScreenHandler() override;
 
   // Gets localized strings to be used on the page.
@@ -65,6 +60,13 @@ class BaseScreenHandler : public content::WebUIMessageHandler,
     return async_assets_load_id_;
   }
 
+  // Set the prefix used when running CallJs with a method. For example,
+  //    set_call_js_prefix("Oobe")
+  //    CallJs("lock") -> Invokes JS global named "Oobe.lock"
+  void set_call_js_prefix(const std::string& prefix) {
+    js_screen_path_prefix_ = prefix + ".";
+  }
+
  protected:
   // All subclasses should implement this method to provide localized values.
   virtual void DeclareLocalizedValues(
@@ -178,9 +180,9 @@ class BaseScreenHandler : public content::WebUIMessageHandler,
   void HandleContextChanged(const base::DictionaryValue* diff);
 
   // Keeps whether page is ready.
-  bool page_is_ready_;
+  bool page_is_ready_ = false;
 
-  BaseScreen* base_screen_;
+  BaseScreen* base_screen_ = nullptr;
 
   // Full name of the corresponding JS screen object. Can be empty, if
   // there are no corresponding screen object or several different