Port messages sent by WebIDBCursorImpl to Mojo.

mojo/public/cpp/bindings/associated_group.h

Index: mojo/public/cpp/bindings/associated_group.h
diff --git a/mojo/public/cpp/bindings/associated_group.h b/mojo/public/cpp/bindings/associated_group.h
index b1c692acd2393cb4052cf33747863122078e28dc..d391fc1b755562c479a82637bd04a69d8dd156b1 100644
--- a/mojo/public/cpp/bindings/associated_group.h
+++ b/mojo/public/cpp/bindings/associated_group.h
@@ -11,6 +11,7 @@
 #include "mojo/public/cpp/bindings/associated_interface_ptr_info.h"
 #include "mojo/public/cpp/bindings/associated_interface_request.h"
 #include "mojo/public/cpp/bindings/bindings_export.h"
+#include "mojo/public/cpp/bindings/lib/multiplex_router.h"
 #include "mojo/public/cpp/bindings/scoped_interface_endpoint_handle.h"
 
 namespace mojo {
@@ -86,6 +87,33 @@ class MOJO_CPP_BINDINGS_EXPORT AssociatedGroup {
   scoped_refptr<AssociatedGroupController> controller_;
 };
 
+// Creates an associated interface proxy in its own AssociatedGroup.
+template <typename Interface>
+AssociatedInterfaceRequest<Interface> GetProxyForTesting(

[yzshen1, 2016/11/15 17:39:50]

Does it make sense to:
- move this function to associated_interface_ptr.h;
- change the first param to AssociatedInterfacePtr (instead of Info)?

[Reilly Grant (use Gerrit), 2016/11/15 17:43:11]

I tried putting it in associated_interface_ptr_info.h but that created a
circular dependency with associated_group.h.
Mojo passes associated interfaces as AssociatedInterfacePtrInfo and so that is
what WebIDBCursorImpl expects as an argument. This is useful because it means
that I can pass it around for a little while before binding it to a thread. That
said, it's easy enough to make the first param an AssociatedInterfacePtr and
just PassInterface() it into WebIDBCursorImpl. However, since
CreateAssociatedInterface() also takes an AssociatedInterfacePtrInfo this seemed
more natural.

[yzshen1, 2016/11/15 17:59:35]

I meant associated_interface_ptr.h (instead of associated_interface_ptr_info.h).
It has GetProxy/GetDummyProxyForTesting there already. And it shouldn't have
circular dependency issue.

Maybe we should move such testing utils to a separate file?
Using AssociatedInterfacePtr* is more consistent with other
GetPorxy()/GetDummyProxyForTesting() functions. And also the word "Proxy"
usually means Ptr instead of PtrInfo.

Maybe an alternative is to name it CreateAssociatedInterfaceForTesting, and have
similar signature as AssociatedGroup::CreateAssociatedInterface?

+    AssociatedInterfacePtrInfo<Interface>* ptr_info,
+    scoped_refptr<base::SingleThreadTaskRunner> runner =
+        base::ThreadTaskRunnerHandle::Get()) {
+  MessagePipe pipe;
+  using internal::MultiplexRouter;
+  scoped_refptr<MultiplexRouter> router0 = new MultiplexRouter(
+      std::move(pipe.handle0), MultiplexRouter::MULTI_INTERFACE, true, runner);
+  scoped_refptr<MultiplexRouter> router1 = new MultiplexRouter(
+      std::move(pipe.handle1), MultiplexRouter::MULTI_INTERFACE, false, runner);
+
+  AssociatedInterfaceRequest<Interface> request;
+  router1->CreateAssociatedGroup()->CreateAssociatedInterface(
+      AssociatedGroup::WILL_PASS_PTR, ptr_info, &request);
+
+  // Emulate passing |ptr_info| across a pipe.
+  ScopedInterfaceEndpointHandle handle = ptr_info->PassHandle();
+  CHECK(!handle.is_local());
+  *ptr_info = AssociatedInterfacePtrInfo<Interface>(
+      router0->CreateLocalEndpointHandle(handle.release()),
+      ptr_info->version());
+
+  return request;
+}
+
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_ASSOCIATED_GROUP_H_