Track where WebContents are created in order to better understand issue.

chrome/browser/ui/cocoa/profiles/user_manager_mac.mm

Index: chrome/browser/ui/cocoa/profiles/user_manager_mac.mm
diff --git a/chrome/browser/ui/cocoa/profiles/user_manager_mac.mm b/chrome/browser/ui/cocoa/profiles/user_manager_mac.mm
index e5bf1c25d50a7d97f1b32c42156725e7f5967ae0..b671e60f1ff0b78713976f47aec2344297945832 100644
--- a/chrome/browser/ui/cocoa/profiles/user_manager_mac.mm
+++ b/chrome/browser/ui/cocoa/profiles/user_manager_mac.mm
@@ -28,6 +28,7 @@
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_delegate.h"
+#include "content/public/browser/web_contents_source.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 #include "ui/events/keycodes/keyboard_codes.h"
 
@@ -194,6 +195,8 @@ class ReauthDialogDelegate : public UserManager::ReauthDialogObserver,
 
     reauthWebContents_.reset(content::WebContents::Create(
         content::WebContents::CreateParams(profile)));
+    WebContentsSource::CreateForWebContentsAndLocation(reauthWebContents_.get(),
+                                                       FROM_HERE);
     window.get().contentView = reauthWebContents_->GetNativeView();
     webContentsDelegate_.reset(
        new ReauthDialogDelegate(reauthWebContents_.get(), emailAddress_));
@@ -293,6 +296,8 @@ class ReauthDialogDelegate : public UserManager::ReauthDialogObserver,
     // Initialize the web view.
     webContents_.reset(content::WebContents::Create(
         content::WebContents::CreateParams(profile)));
+    WebContentsSource::CreateForWebContentsAndLocation(webContents_.get(),
+                                                       FROM_HERE);
     window.contentView = webContents_->GetNativeView();
     webContentsDelegate_.reset(new UserManagerWebContentsDelegate());
     webContents_->SetDelegate(webContentsDelegate_.get());