arc: Remove ArcBridgeInstance

Use the message pipe attached to the invitation for ArcBridgeHost.
This requires Android version which includes the corresponding change.

BUG=b:151063537
TEST=Launch Play Store

Change-Id: Id326252882bdd3f845f4a126a91a8f5fb2b77b5c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2094840Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Commit-Queue: Ryo Hashimoto <hashimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756897}

components/arc/mojom/arc_bridge.mojom

@@ -229,10 +229,3 @@ interface ArcBridgeHost {
   // Notifies Chrome that the WallpaperInstance interface is ready.
   [MinVersion=18] OnWallpaperInstanceReady@124(WallpaperInstance instance_ptr);
 };
-
-interface ArcBridgeInstance {
-  // Establishes full-duplex communication with the host.
-  // |host_ptr| is the MessagePipe endpoint that is bound to the
-  // ArcBridgeHostPtr binding.
-  Init@0(ArcBridgeHost host_ptr);
-};

components/arc/session/arc_bridge_host_impl.cc

@@ -69,17 +69,12 @@ namespace arc {
 
 ArcBridgeHostImpl::ArcBridgeHostImpl(
     ArcBridgeService* arc_bridge_service,
-    mojo::PendingRemote<mojom::ArcBridgeInstance> instance)
+    mojo::PendingReceiver<mojom::ArcBridgeHost> pending_receiver)
     : arc_bridge_service_(arc_bridge_service),
-      receiver_(this),
-      instance_(std::move(instance)) {
+      receiver_(this, std::move(pending_receiver)) {
   DCHECK(arc_bridge_service_);
-  DCHECK(instance_.is_bound());
-  instance_.set_disconnect_handler(
+  receiver_.set_disconnect_handler(
       base::BindOnce(&ArcBridgeHostImpl::OnClosed, base::Unretained(this)));
-  mojom::ArcBridgeHostPtr host_proxy;
-  receiver_.Bind(mojo::MakeRequest(&host_proxy));
-  instance_->Init(std::move(host_proxy));
 }
 
 ArcBridgeHostImpl::~ArcBridgeHostImpl() {
@@ -364,9 +359,7 @@ void ArcBridgeHostImpl::OnClosed() {
 
   // Close all mojo channels.
   mojo_channels_.clear();
-  instance_.reset();
-  if (receiver_.is_bound())
-    receiver_.reset();
+  receiver_.reset();
 
   arc_bridge_service_->ObserveAfterArcBridgeClosed();
 }

components/arc/session/arc_bridge_host_impl.h

@@ -23,9 +23,9 @@ class ArcBridgeService;
 class MojoChannelBase;
 
 // Implementation of the ArcBridgeHost.
-// The lifetime of ArcBridgeHost and ArcBridgeInstance mojo channels are tied
-// to this instance. Also, any ARC related Mojo channel will be closed if
-// either ArcBridgeHost or ArcBridgeInstance Mojo channels is closed on error.
+// The lifetime of ArcBridgeHost mojo channel is tied to this instance.
+// Also, any ARC related Mojo channel will be closed if ArcBridgeHost Mojo
+// channel is closed on error.
 // When ARC Instance (not Host) Mojo channel gets ready (= passed via
 // OnFooInstanceReady(), and the QueryVersion() gets completed), then this sets
 // the raw pointer to the ArcBridgeService so that other services can access
@@ -33,8 +33,9 @@ class MojoChannelBase;
 // Note that ArcBridgeService must be alive while ArcBridgeHostImpl is alive.
 class ArcBridgeHostImpl : public mojom::ArcBridgeHost {
  public:
-  ArcBridgeHostImpl(ArcBridgeService* arc_bridge_service,
-                    mojo::PendingRemote<mojom::ArcBridgeInstance> instance);
+  ArcBridgeHostImpl(
+      ArcBridgeService* arc_bridge_service,
+      mojo::PendingReceiver<mojom::ArcBridgeHost> pending_receiver);
   ~ArcBridgeHostImpl() override;
 
   // ArcBridgeHost overrides.
@@ -141,7 +142,6 @@ class ArcBridgeHostImpl : public mojom::ArcBridgeHost {
   ArcBridgeService* const arc_bridge_service_;
 
   mojo::Receiver<mojom::ArcBridgeHost> receiver_;
-  mojo::Remote<mojom::ArcBridgeInstance> instance_;
 
   // Put as a last member to ensure that any callback tied to the elements
   // is not invoked.

components/arc/session/arc_session_impl.cc

@@ -277,11 +277,16 @@ mojo::ScopedMessagePipeHandle ArcSessionDelegateImpl::ConnectMojoInternal(
   std::vector<base::ScopedFD> fds;
   fds.emplace_back(channel.TakeRemoteEndpoint().TakePlatformHandle().TakeFD());
 
+  // Version of protocol chrome is using.
+  uint8_t protocol_version = 0;
+
   // We need to send the length of the message as a single byte, so make sure it
   // fits.
   DCHECK_LT(token.size(), 256u);
   uint8_t message_length = static_cast<uint8_t>(token.size());
-  struct iovec iov[] = {{&message_length, sizeof(message_length)},
+
+  struct iovec iov[] = {{&protocol_version, sizeof(protocol_version)},
+                        {&message_length, sizeof(message_length)},
                         {const_cast<char*>(token.c_str()), token.size()}};
   ssize_t result = mojo::SendmsgWithHandles(connection_fd.get(), iov,
                                             sizeof(iov) / sizeof(iov[0]), fds);
@@ -303,8 +308,8 @@ void ArcSessionDelegateImpl::OnMojoConnected(
   }
 
   std::move(callback).Run(std::make_unique<ArcBridgeHostImpl>(
-      arc_bridge_service_, mojo::PendingRemote<mojom::ArcBridgeInstance>(
-                               std::move(server_pipe), 0u)));
+      arc_bridge_service_,
+      mojo::PendingReceiver<mojom::ArcBridgeHost>(std::move(server_pipe))));
 }
 
 }  // namespace