Move content's shell connections to the IO thread

content/browser/browser_context.cc

Index: content/browser/browser_context.cc
diff --git a/content/browser/browser_context.cc b/content/browser/browser_context.cc
index a1c1d0acdfc24b70a7ddeb5ac27cd5edbf63339c..47bc07ccadd700d9280ee3c716386a475b070cc3 100644
--- a/content/browser/browser_context.cc
+++ b/content/browser/browser_context.cc
@@ -152,7 +152,9 @@ class BrowserContextShellConnectionHolder
       std::unique_ptr<shell::Connection> connection,
       shell::mojom::ShellClientRequest request)
       : root_connection_(std::move(connection)),
-        shell_connection_(MojoShellConnection::Create(std::move(request))) {}
+        shell_connection_(MojoShellConnection::Create(
+            std::move(request),
+            BrowserThread::GetMessageLoopProxyForThread(BrowserThread::IO))) {}
   ~BrowserContextShellConnectionHolder() override {}
 
   MojoShellConnection* shell_connection() { return shell_connection_.get(); }