Mojo C++ bindings: add a MakeRequest overload that binds InterfacePtrInfo.

BUG=None

Review-Url: https://codereview.chromium.org/2855303003
Cr-Commit-Position: refs/heads/master@{#469448}

mojo/public/cpp/bindings/interface_ptr.h

@@ -31,10 +31,10 @@ namespace mojo {
 // to a message pipe. All calls to this class or the proxy should be from the
 // same thread that bound it. If you need to move the proxy to a different
 // thread, extract the InterfacePtrInfo (containing just the message pipe and
-// any version information) using PassInterface(), pass it to a different
-// thread, and create and bind a new InterfacePtr from that thread. If an
-// InterfacePtr is not bound to a message pipe, it may be bound or destroyed on
-// any thread.
+// any version information) using PassInterface() on the original thread, pass
+// it to a different thread, and create and bind a new InterfacePtr from that
+// thread. If an InterfacePtr is not bound to a message pipe, it may be bound or
+// destroyed on any thread.
 template <typename Interface>
 class InterfacePtr {
  public:

mojo/public/cpp/bindings/interface_request.h

@@ -46,6 +46,15 @@ class InterfaceRequest {
     Bind(std::move(pipe.handle1));
   }
 
+  // Similar to the constructor above, but binds one end of the message pipe to
+  // an InterfacePtrInfo instance.
+  explicit InterfaceRequest(InterfacePtrInfo<Interface>* ptr_info) {
+    MessagePipe pipe;
+    ptr_info->set_handle(std::move(pipe.handle0));
+    ptr_info->set_version(0u);
+    Bind(std::move(pipe.handle1));
+  }
+
   // Takes the message pipe from another InterfaceRequest.
   InterfaceRequest(InterfaceRequest&& other) {
     handle_ = std::move(other.handle_);
@@ -163,6 +172,13 @@ InterfaceRequest<Interface> MakeRequest(
   return InterfaceRequest<Interface>(ptr, runner);
 }
 
+// Similar to the constructor above, but binds one end of the message pipe to
+// an InterfacePtrInfo instance.
+template <typename Interface>
+InterfaceRequest<Interface> MakeRequest(InterfacePtrInfo<Interface>* ptr_info) {
+  return InterfaceRequest<Interface>(ptr_info);
+}
+
 // Fuses an InterfaceRequest<T> endpoint with an InterfacePtrInfo<T> endpoint.
 // Returns |true| on success or |false| on failure.
 template <typename Interface>

mojo/public/cpp/bindings/tests/interface_ptr_unittest.cc

@@ -704,15 +704,15 @@ class PingTestImpl : public sample::PingTest {
 
 // Tests that FuseProxy does what it's supposed to do.
 TEST_F(InterfacePtrTest, Fusion) {
-  sample::PingTestPtr proxy;
-  PingTestImpl impl(MakeRequest(&proxy));
+  sample::PingTestPtrInfo proxy_info;
+  PingTestImpl impl(MakeRequest(&proxy_info));
 
   // Create another PingTest pipe.
   sample::PingTestPtr ptr;
   sample::PingTestRequest request(&ptr);
 
   // Fuse the new pipe to the one hanging off |impl|.
-  EXPECT_TRUE(FuseInterface(std::move(request), proxy.PassInterface()));
+  EXPECT_TRUE(FuseInterface(std::move(request), std::move(proxy_info)));
 
   // Ping!
   bool called = false;