Clean up ref when AuthStatusConsumer goes away

ExtendedAuthenticator(Impl) could out-live AuthStatusConsumer.
Hence AuthStatusConsumer should clean up its reference in
the ExtendedAuthenticator before it is released.

Bug: 788987
Change-Id: Ie489da7b0c085cbfa7723b01692855c3457cf90a
Reviewed-on: https://chromium-review.googlesource.com/794842Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Commit-Queue: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#519899}

chrome/browser/chromeos/extensions/quick_unlock_private/quick_unlock_private_api.cc

@@ -285,7 +285,10 @@ QuickUnlockPrivateGetCredentialRequirementsFunction::Run() {
 QuickUnlockPrivateSetModesFunction::QuickUnlockPrivateSetModesFunction()
     : chrome_details_(this) {}
 
-QuickUnlockPrivateSetModesFunction::~QuickUnlockPrivateSetModesFunction() {}
+QuickUnlockPrivateSetModesFunction::~QuickUnlockPrivateSetModesFunction() {
+  if (extended_authenticator_)
+    extended_authenticator_->SetConsumer(nullptr);
+}
 
 void QuickUnlockPrivateSetModesFunction::SetAuthenticatorAllocatorForTesting(
     const QuickUnlockPrivateSetModesFunction::AuthenticatorAllocator&
@@ -347,6 +350,7 @@ ExtensionFunction::ResponseAction QuickUnlockPrivateSetModesFunction::Run() {
 
   // Lazily allocate the authenticator. We do this here, instead of in the ctor,
   // so that tests can install a fake.
+  DCHECK(!extended_authenticator_);
   if (authenticator_allocator_.is_null())
     extended_authenticator_ = chromeos::ExtendedAuthenticator::Create(this);
   else

chrome/browser/chromeos/login/lock/screen_locker.cc

@@ -573,8 +573,11 @@ ScreenLocker::~ScreenLocker() {
   VLOG(1) << "Destroying ScreenLocker " << this;
   DCHECK(base::MessageLoopForUI::IsCurrent());
 
-  if (authenticator_.get())
+  if (authenticator_)
     authenticator_->SetConsumer(nullptr);
+  if (extended_authenticator_)
+    extended_authenticator_->SetConsumer(nullptr);
+
   ClearErrors();
 
   screen_locker_ = nullptr;