Reland: CrOS - Login Screen - Minor cleanup

Reverted due to a merge conflict with another CL.

Original change's description:
> CrOS - Login Screen - Minor cleanup
>
> Rename AnimationState to UiState and use it to determine the
> visibility of elements. Remove multiple variables in favor of
> UiState.
>
> Bug: 1075994
> Change-Id: I0d7413fb173dadbff22cde0eb3af6f43586bdee2
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2352883
> Commit-Queue: Renato Silva <rrsilva@google.com>
> Reviewed-by: Denis Kuznetsov [CET] <antrim@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#798780}

Bug: 1075994
Change-Id: I0e2c05b692ddb807930455fca6b5a2216c0a16e1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2362183Reviewed-by: Denis Kuznetsov [CET] <antrim@chromium.org>
Reviewed-by: Roman Aleksandrov <raleksandrov@google.com>
Commit-Queue: Renato Silva <rrsilva@google.com>
Cr-Commit-Position: refs/heads/master@{#799680}

ash/login/ui/lock_contents_view.cc

@@ -1763,7 +1763,7 @@ void LockContentsView::LayoutAuth(LoginBigUserView* to_update,
   DCHECK(to_update);
 
   auto capture_animation_state_pre_layout = [&](LoginBigUserView* view) {
-    if (!animate || !view)
+    if (!view)
       return;
     if (view->auth_user())
       view->auth_user()->CaptureStateForAnimationPreLayout();
@@ -1818,10 +1818,10 @@ void LockContentsView::LayoutAuth(LoginBigUserView* to_update,
   };
 
   auto apply_animation_post_layout = [&](LoginBigUserView* view) {
-    if (!animate || !view)
+    if (!view)
       return;
     if (view->auth_user())
-      view->auth_user()->ApplyAnimationPostLayout();
+      view->auth_user()->ApplyAnimationPostLayout(animate);
   };
 
   // The high-level layout flow:

ash/login/ui/login_auth_user_view.h

@@ -68,7 +68,7 @@ class ASH_EXPORT LoginAuthUserView : public NonAccessibleView,
   // This is determined by the current authentication methods
   // that a user has.
   enum class InputFieldMode {
-    DISABLED,          // Not showing any input field.
+    NONE,              // Not showing any input field.
     PASSWORD_ONLY,     // No PIN set. Password only field.
     PIN_AND_PASSWORD,  // PIN set.
   };
@@ -125,7 +125,8 @@ class ASH_EXPORT LoginAuthUserView : public NonAccessibleView,
 
   // Set the displayed set of auth methods. |auth_methods| contains or-ed
   // together AuthMethod values. |auth_metadata| provides additional control
-  // parameters for the view.
+  // parameters for the view. Must always be called in conjunction with
+  // `CaptureStateForAnimationPreLayout` and `ApplyAnimationPostLayout`.
   void SetAuthMethods(
       uint32_t auth_methods,
       AuthMethodsMetadata auth_metadata = AuthMethodsMetadata());
@@ -140,8 +141,9 @@ class ASH_EXPORT LoginAuthUserView : public NonAccessibleView,
   // animation.
   void CaptureStateForAnimationPreLayout();
   // Applies animation based on current layout state compared to the most
-  // recently captured state.
-  void ApplyAnimationPostLayout();
+  // recently captured state. If `animate` is false, the previous UI state
+  // is released and no animation is performed.
+  void ApplyAnimationPostLayout(bool animate);
 
   // Update the displayed name, icon, etc to that of |user|.
   void UpdateForUser(const LoginUserInfo& user);
@@ -172,7 +174,7 @@ class ASH_EXPORT LoginAuthUserView : public NonAccessibleView,
   void ButtonPressed(views::Button* sender, const ui::Event& event) override;
 
  private:
-  struct AnimationState;
+  struct UiState;
   class FingerprintView;
   class ChallengeResponseView;
   class DisabledAuthMessageView;
@@ -210,6 +212,9 @@ class ASH_EXPORT LoginAuthUserView : public NonAccessibleView,
   // starts the asynchronous authentication process against a security token.
   void AttemptAuthenticateWithChallengeResponse();
 
+  // Updates the element in focus. Used in `ApplyAnimationPostLayout`.
+  void UpdateFocus();
+
   // Determines the mode of the input field based on the available
   // authentication methods.
   void UpdateInputFieldMode();
@@ -230,7 +235,7 @@ class ASH_EXPORT LoginAuthUserView : public NonAccessibleView,
   AuthMethodsMetadata auth_metadata_ = AuthMethodsMetadata();
 
   // Controls which input field is currently being shown.
-  InputFieldMode input_field_mode_ = InputFieldMode::DISABLED;
+  InputFieldMode input_field_mode_ = InputFieldMode::NONE;
 
   LoginUserView* user_view_ = nullptr;
   LoginPasswordView* password_view_ = nullptr;
@@ -252,10 +257,10 @@ class ASH_EXPORT LoginAuthUserView : public NonAccessibleView,
   const OnAuthCallback on_auth_;
   const LoginUserView::OnTap on_tap_;
 
-  // Animation state that was cached from before a layout. Generated by
-  // |CaptureStateForAnimationPreLayout| and consumed by
-  // |ApplyAnimationPostLayout|.
-  std::unique_ptr<AnimationState> cached_animation_state_;
+  // UI state that was stored before setting new authentication methods.
+  // Generated by `CaptureStateForAnimationPreLayout` and consumed by
+  // `ApplyAnimationPostLayout`.
+  std::unique_ptr<UiState> previous_state_;
 
   base::WeakPtrFactory<LoginAuthUserView> weak_factory_{this};
 

ash/login/ui/login_auth_user_view_unittest.cc

@@ -65,7 +65,9 @@ class LoginAuthUserViewUnittest : public LoginTestBase {
     auth_metadata.show_pinpad_for_pw = show_pinpad_for_pw;
     auth_metadata.virtual_keyboard_visible = virtual_keyboard_visible;
     auth_metadata.autosubmit_pin_length = autosubmit_pin_length;
+    view_->CaptureStateForAnimationPreLayout();
     view_->SetAuthMethods(auth_methods, auth_metadata);
+    view_->ApplyAnimationPostLayout(true);
   }
 
   LoginUserInfo user_;
@@ -183,18 +185,14 @@ TEST_F(LoginAuthUserViewUnittest,
   password_test.textfield()->SetText(base::ASCIIToUTF16("Hello"));
 
   // Enable some other auth method (PIN), password is not cleared.
-  view_->CaptureStateForAnimationPreLayout();
+  EXPECT_TRUE(has_password());
   SetAuthMethods(LoginAuthUserView::AUTH_PASSWORD |
                  LoginAuthUserView::AUTH_PIN);
   EXPECT_TRUE(has_password());
-  view_->ApplyAnimationPostLayout();
-  EXPECT_TRUE(has_password());
 
   // Disable password, password is cleared.
-  view_->CaptureStateForAnimationPreLayout();
-  SetAuthMethods(LoginAuthUserView::AUTH_NONE);
   EXPECT_TRUE(has_password());
-  view_->ApplyAnimationPostLayout();
+  SetAuthMethods(LoginAuthUserView::AUTH_NONE);
   EXPECT_FALSE(has_password());
 }