ipc: Change the timing of the construction of the attachment broker.

content/common/child_process_host_impl.cc

Index: content/common/child_process_host_impl.cc
diff --git a/content/common/child_process_host_impl.cc b/content/common/child_process_host_impl.cc
index 071d96d207d0c424f5a0976a885a1dc3f96e7a4e..0c1fab2d4abb8433221ddc7b7d347ebae41233e7 100644
--- a/content/common/child_process_host_impl.cc
+++ b/content/common/child_process_host_impl.cc
@@ -111,6 +111,14 @@ ChildProcessHostImpl::ChildProcessHostImpl(ChildProcessHostDelegate* delegate)
 #if defined(OS_WIN)
   AddFilter(new FontCacheDispatcher());
 #endif
+#if USE_ATTACHMENT_BROKER
+  // Ensure that the privileged attachment broker gets constructed early in the
+  // life cycle of a child process. This ensures that when a test is being run
+  // in one of the single process modes, the global attachment broker is the
+  // privileged attachment broker, rather than an unprivileged attachment
+  // broker.
+  GetAttachmentBroker();
+#endif
 }
 
 ChildProcessHostImpl::~ChildProcessHostImpl() {