Use ScopedObserver in MergeSessionNavigationThrottle

Bug: 875284
Change-Id: Id802fe60adaa4f49af2105fffedca7a024c0c82d
Reviewed-on: https://chromium-review.googlesource.com/1211107
Commit-Queue: Carlos IL <carlosil@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589304}

chrome/browser/chromeos/login/signin/merge_session_navigation_throttle.cc

@@ -40,7 +40,7 @@ MergeSessionNavigationThrottle::Create(content::NavigationHandle* handle) {
 
 MergeSessionNavigationThrottle::MergeSessionNavigationThrottle(
     content::NavigationHandle* handle)
-    : NavigationThrottle(handle) {
+    : NavigationThrottle(handle), login_manager_observer_(this) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 }
 
@@ -87,7 +87,7 @@ bool MergeSessionNavigationThrottle::BeforeDefer() {
   chromeos::OAuth2LoginManager* manager =
       GetOAuth2LoginManager(navigation_handle()->GetWebContents());
   if (manager && manager->ShouldBlockTabLoading()) {
-    manager->AddObserver(this);
+    login_manager_observer_.Add(manager);
     proceed_timer_.Start(FROM_HERE, kTotalWaitTime, this,
                          &MergeSessionNavigationThrottle::Proceed);
     return true;
@@ -100,7 +100,7 @@ void MergeSessionNavigationThrottle::Proceed() {
   chromeos::OAuth2LoginManager* manager =
       GetOAuth2LoginManager(navigation_handle()->GetWebContents());
   if (manager) {
-    manager->RemoveObserver(this);
+    login_manager_observer_.Remove(manager);
   }
   Resume();
 }

chrome/browser/chromeos/login/signin/merge_session_navigation_throttle.h

@@ -9,6 +9,7 @@
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/scoped_observer.h"
 #include "base/timer/timer.h"
 #include "chrome/browser/chromeos/login/signin/oauth2_login_manager.h"
 #include "content/public/browser/navigation_throttle.h"
@@ -52,6 +53,10 @@ class MergeSessionNavigationThrottle
   // navigation.
   void Proceed();
 
+  ScopedObserver<chromeos::OAuth2LoginManager,
+                 chromeos::OAuth2LoginManager::Observer>
+      login_manager_observer_;
+
   base::OneShotTimer proceed_timer_;
 
   DISALLOW_COPY_AND_ASSIGN(MergeSessionNavigationThrottle);

chrome/browser/chromeos/login/signin/merge_session_navigation_throttle_unittest.cc

@@ -29,6 +29,15 @@ class MergeSessionNavigationThrottleTest
  public:
   MergeSessionNavigationThrottleTest() = default;
 
+  bool ManagerHasObservers() {
+    OAuth2LoginManager* manager = GetOAuth2LoginManager();
+    if (!manager) {
+      ADD_FAILURE();
+      return false;
+    }
+    return manager->observer_list_.might_have_observers();
+  }
+
  protected:
   void SetUp() override {
     ChromeRenderViewHostTestHarness::SetUp();
@@ -89,6 +98,7 @@ TEST_F(MergeSessionNavigationThrottleTest, NotThrottled) {
       GURL(kURL), web_contents());
   navigation->Start();
   EXPECT_FALSE(navigation->IsDeferred());
+  EXPECT_FALSE(ManagerHasObservers());
 }
 
 // Tests navigations are deferred when merge session is in progress, and
@@ -104,6 +114,7 @@ TEST_F(MergeSessionNavigationThrottleTest, Throttled) {
   SetMergeSessionState(OAuth2LoginManager::SESSION_RESTORE_DONE);
   navigation->Wait();
   EXPECT_FALSE(navigation->IsDeferred());
+  EXPECT_FALSE(ManagerHasObservers());
 }
 
 // Tests navigations are not deferred if merge session started over 60
@@ -116,6 +127,7 @@ TEST_F(MergeSessionNavigationThrottleTest, Timeout) {
       GURL(kURL), web_contents());
   navigation->Start();
   EXPECT_FALSE(navigation->IsDeferred());
+  EXPECT_FALSE(ManagerHasObservers());
 }
 
 }  // namespace chromeos