Check for null WebContents in LoginHandler::GetWebContentsForLogin

Bug: 885376
Change-Id: Ic1b4075a169512103994edabc53b5d1b6daffb10
Reviewed-on: https://chromium-review.googlesource.com/c/1325190
Commit-Queue: Carlos IL <carlosil@chromium.org>
Reviewed-by: David Benjamin <davidben@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607010}

chrome/browser/ui/login/login_handler.cc

@@ -164,8 +164,11 @@ WebContents* LoginHandler::GetWebContentsForLogin() const {
 }
 
 password_manager::PasswordManager* LoginHandler::GetPasswordManagerForLogin() {
+  WebContents* contents = GetWebContentsForLogin();
+  if (!contents)
+    return nullptr;
   password_manager::PasswordManagerClient* client =
-      ChromePasswordManagerClient::FromWebContents(GetWebContentsForLogin());
+      ChromePasswordManagerClient::FromWebContents(contents);
   return client ? client->GetPasswordManager() : nullptr;
 }