Revert of Implement inline signin with iframe

chrome/browser/chrome_content_browser_client.cc

Index: chrome/browser/chrome_content_browser_client.cc
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index e89e889721322663e821a851980ca8dffe1a9b45..bbb5a8bbbcdb3d2e29e3ded70a6fd1f278f86361 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -802,10 +802,6 @@
       *in_memory = false;
       partition_name->clear();
     }
-  } else if (site.GetOrigin().spec() == kChromeUIChromeSigninURL) {
-    // Chrome signin page has an embedded iframe of extension and web content,
-    // thus it must be isolated from other webUI pages.
-    *partition_domain = chrome::kChromeUIChromeSigninHost;
   }
 
   // Assert that if |can_be_default| is false, the code above must have found a