Add a NavigationThrottle to the public content/ interface

content/test/web_contents_observer_sanity_checker.cc

Index: content/test/web_contents_observer_sanity_checker.cc
diff --git a/content/test/web_contents_observer_sanity_checker.cc b/content/test/web_contents_observer_sanity_checker.cc
index 82bcb60461840a005453f0d271ce50cd3de1e7bd..18d38ae0549037f2b752ad7cd00b9938c8c118f4 100644
--- a/content/test/web_contents_observer_sanity_checker.cc
+++ b/content/test/web_contents_observer_sanity_checker.cc
@@ -129,6 +129,7 @@ void WebContentsObserverSanityChecker::DidStartNavigation(
   CHECK(navigation_handle->GetNetErrorCode() == net::OK);
   CHECK(!navigation_handle->HasCommittedDocument());
   CHECK(!navigation_handle->HasCommittedErrorPage());
+  CHECK_EQ(navigation_handle->GetWebContents(), web_contents());
 
   ongoing_navigations_.insert(navigation_handle);
 }
@@ -141,6 +142,7 @@ void WebContentsObserverSanityChecker::DidRedirectNavigation(
   CHECK(navigation_handle->GetNetErrorCode() == net::OK);
   CHECK(!navigation_handle->HasCommittedDocument());
   CHECK(!navigation_handle->HasCommittedErrorPage());
+  CHECK_EQ(navigation_handle->GetWebContents(), web_contents());
 }
 
 void WebContentsObserverSanityChecker::ReadyToCommitNavigation(
@@ -163,6 +165,7 @@ void WebContentsObserverSanityChecker::DidCommitNavigation(
                 navigation_handle->GetNetErrorCode() == net::OK);
   CHECK_IMPLIES(navigation_handle->HasCommittedErrorPage(),
                 navigation_handle->GetNetErrorCode() != net::OK);
+  CHECK_EQ(navigation_handle->GetWebContents(), web_contents());
 
   ongoing_committed_navigations_.insert(navigation_handle);
 }
@@ -178,6 +181,7 @@ void WebContentsObserverSanityChecker::DidFinishNavigation(
                 navigation_handle->GetNetErrorCode() == net::OK);
   CHECK_IMPLIES(navigation_handle->HasCommittedErrorPage(),
                 navigation_handle->GetNetErrorCode() != net::OK);
+  CHECK_EQ(navigation_handle->GetWebContents(), web_contents());
 
   if (NavigationIsOngoingAndCommitted(navigation_handle))
     ongoing_committed_navigations_.erase(navigation_handle);