Mojo C++ Bindings: Eliminate unbound ThreadSafeInterfacePtr

ipc/ipc_channel.h

Index: ipc/ipc_channel.h
diff --git a/ipc/ipc_channel.h b/ipc/ipc_channel.h
index 1c0a89d20d5e6ab95fa27e5ee9ad004e0ae11f2f..4a2014412af48ffbf4ea0d79e545ceccc0e98ed6 100644
--- a/ipc/ipc_channel.h
+++ b/ipc/ipc_channel.h
@@ -18,6 +18,7 @@
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
+#include "ipc/ipc.mojom.h"
 #include "ipc/ipc_channel_handle.h"
 #include "ipc/ipc_message.h"
 #include "ipc/ipc_sender.h"
@@ -25,6 +26,7 @@
 #include "mojo/public/cpp/bindings/associated_interface_ptr.h"
 #include "mojo/public/cpp/bindings/associated_interface_request.h"
 #include "mojo/public/cpp/bindings/scoped_interface_endpoint_handle.h"
+#include "mojo/public/cpp/bindings/thread_safe_interface_ptr.h"
 
 #if defined(OS_POSIX)
 #include <sys/types.h>
@@ -94,6 +96,11 @@ class IPC_EXPORT Channel : public Sender {
     // with this Channel. Must be safe to call from any thread.
     virtual mojo::AssociatedGroup* GetAssociatedGroup() = 0;
 
+    // Returns a ThreadSafeForwarded for this channel which can be used to
+    // safely send mojom::Channel requests from arbitrary threads.
+    virtual std::unique_ptr<mojo::ThreadSafeForwarder<mojom::Channel>>
+    CreateThreadSafeChannel() = 0;
+
     // Adds an interface factory to this channel for interface |name|. Must be
     // safe to call from any thread.
     virtual void AddGenericAssociatedInterface(