cros: Only preload the lock screen; do not reuse it.

chrome/browser/chromeos/login/lock/webui_screen_locker.h

Index: chrome/browser/chromeos/login/lock/webui_screen_locker.h
diff --git a/chrome/browser/chromeos/login/lock/webui_screen_locker.h b/chrome/browser/chromeos/login/lock/webui_screen_locker.h
index 2a49acd28292e8d7f4a0a1ae8c30ea6048774dc1..91fe5349499b6b582220acd59d132f7571928c0c 100644
--- a/chrome/browser/chromeos/login/lock/webui_screen_locker.h
+++ b/chrome/browser/chromeos/login/lock/webui_screen_locker.h
@@ -55,9 +55,9 @@ class WebUIScreenLocker : public WebUILoginView,
                           public display::DisplayObserver,
                           public content::WebContentsObserver {
  public:
-  // Returns true if the lock screen should be shared.
-  static bool ShouldShareLockScreen();
-  static void Preload();
+  // Request lock screen preload when the user is idle. Does nothing if
+  // preloading is disabled or if the preload hueristics return false.
+  static void RequestPreload();
 
   explicit WebUIScreenLocker(ScreenLocker* screen_locker);
   ~WebUIScreenLocker() override;
@@ -93,6 +93,11 @@ class WebUIScreenLocker : public WebUILoginView,
   void OnHeaderBarVisible();
 
  private:
+  // Returns true if the lock screen should be preloaded.
+  static bool ShouldPreloadLockScreen();
+  // Helper function that creates and preloads a views::WebView.
+  static std::unique_ptr<views::WebView> DoPreload(Profile* profile);

[xiyuan, 2017/01/06 17:14:25]

nit: move this after "friend" to match existing code

[jdufault, 2017/01/13 19:46:58]

Done.

+
   friend class test::WebUIScreenLockerTester;
 
   // LoginDisplay::Delegate:
@@ -158,6 +163,9 @@ class WebUIScreenLocker : public WebUILoginView,
   // Reset user pod and ensures that user pod is focused.
   void ResetAndFocusUserPod();
 
+  // Configuration settings.
+  WebViewSettings BuildConfigSettings();
+
   // The ScreenLocker that owns this instance.
   ScreenLocker* screen_locker_ = nullptr;