cros: Views login/lock clear password when switching active auth user.

Bug: 855725
Change-Id: I91f6bab46701c9d66bc8b497661c460a7968619f
Reviewed-on: https://chromium-review.googlesource.com/1112075
Commit-Queue: Jacob Dufault <jdufault@chromium.org>
Reviewed-by: Xiaoyin Hu <xiaoyinh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569802}

ash/login/ui/login_auth_user_view.cc

@@ -101,6 +101,26 @@ ui::CallbackLayerAnimationObserver* BuildObserverToHideView(views::View* view) {
       view));
 }
 
+// Clears the password for the given |LoginPasswordView| instance and then
+// deletes itself.
+class ClearPasswordAnimationObserver : public ui::ImplicitAnimationObserver {
+ public:
+  explicit ClearPasswordAnimationObserver(LoginPasswordView* view)
+      : view_(view) {}
+  ~ClearPasswordAnimationObserver() override = default;
+
+  // ui::ImplicitAnimationObserver:
+  void OnImplicitAnimationsCompleted() override {
+    view_->Clear();
+    delete this;
+  }
+
+ private:
+  LoginPasswordView* view_;
+
+  DISALLOW_COPY_AND_ASSIGN(ClearPasswordAnimationObserver);
+};
+
 // A view which has a round border and a fingerprint icon at the center.
 class FingerprintIconView : public views::View {
  public:
@@ -548,6 +568,10 @@ void LoginAuthUserView::ApplyAnimationPostLayout() {
       settings.SetTransitionDuration(base::TimeDelta::FromMilliseconds(
           login_constants::kChangeUserAnimationDurationMs));
       settings.SetTweenType(gfx::Tween::Type::FAST_OUT_SLOW_IN);
+      if (cached_animation_state_->had_password && !has_password) {
+        settings.AddObserver(
+            new ClearPasswordAnimationObserver(password_view_));
+      }
 
       password_view_->layer()->SetOpacity(opacity_end);
     }

ash/login/ui/login_auth_user_view_unittest.cc

@@ -12,6 +12,7 @@
 #include "ash/strings/grit/ash_strings.h"
 #include "base/bind_helpers.h"
 #include "base/run_loop.h"
+#include "base/strings/utf_string_conversions.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/events/event_utils.h"
@@ -163,4 +164,32 @@ TEST_F(LoginAuthUserViewUnittest, OnlineSignInMessage) {
   EXPECT_FALSE(online_sign_in_message->visible());
 }
 
+// Verifies that password is cleared after AUTH_PASSWORD is disabled.
+TEST_F(LoginAuthUserViewUnittest,
+       PasswordClearedAfterAnimationIfPasswordDisabled) {
+  LoginPasswordView::TestApi password_test(view_->password_view());
+  auto has_password = [&]() {
+    return !password_test.textfield()->text().empty();
+  };
+
+  // Set a password.
+  view_->SetAuthMethods(LoginAuthUserView::AUTH_PASSWORD);
+  password_test.textfield()->SetText(base::ASCIIToUTF16("Hello"));
+
+  // Enable some other auth method (PIN), password is not cleared.
+  view_->CaptureStateForAnimationPreLayout();
+  view_->SetAuthMethods(LoginAuthUserView::AUTH_PASSWORD |
+                        LoginAuthUserView::AUTH_PIN);
+  EXPECT_TRUE(has_password());
+  view_->ApplyAnimationPostLayout();
+  EXPECT_TRUE(has_password());
+
+  // Disable password, password is cleared.
+  view_->CaptureStateForAnimationPreLayout();
+  view_->SetAuthMethods(LoginAuthUserView::AUTH_NONE);
+  EXPECT_TRUE(has_password());
+  view_->ApplyAnimationPostLayout();
+  EXPECT_FALSE(has_password());
+}
+
 }  // namespace ash