arc: Move MojoChannel into its own file

Move MojoChannel code out of ArcBridgeHostImpl into its own file
to be shared.

Bug: 768439
Change-Id: I730ae1f498893455f3aa2e768f47893409109768
Reviewed-on: https://chromium-review.googlesource.com/1012136Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Commit-Queue: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550646}

components/arc/BUILD.gn

@@ -153,6 +153,7 @@ static_library("arc_base") {
     "connection_notifier.cc",
     "connection_notifier.h",
     "connection_observer.h",
+    "mojo_channel.h",
   ]
 
   deps = [

components/arc/arc_bridge_host_impl.cc

@@ -10,63 +10,10 @@
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "components/arc/arc_bridge_service.h"
+#include "components/arc/mojo_channel.h"
 
 namespace arc {
 
-// Thin interface to wrap InterfacePtr<T> with type erasure.
-class ArcBridgeHostImpl::MojoChannel {
- public:
-  virtual ~MojoChannel() = default;
-
- protected:
-  MojoChannel() = default;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(MojoChannel);
-};
-
-namespace {
-
-// The thin wrapper for InterfacePtr<T>, where T is one of ARC mojo Instance
-// class.
-template <typename InstanceType, typename HostType>
-class MojoChannelImpl : public ArcBridgeHostImpl::MojoChannel {
- public:
-  MojoChannelImpl(ConnectionHolder<InstanceType, HostType>* holder,
-                  mojo::InterfacePtr<InstanceType> ptr)
-      : holder_(holder), ptr_(std::move(ptr)) {
-    // Delay registration to the ConnectionHolder until the version is ready.
-  }
-
-  ~MojoChannelImpl() override { holder_->CloseInstance(ptr_.get()); }
-
-  void set_connection_error_handler(base::OnceClosure error_handler) {
-    ptr_.set_connection_error_handler(std::move(error_handler));
-  }
-
-  void QueryVersion() {
-    // Note: the callback will not be called if |ptr_| is destroyed.
-    ptr_.QueryVersion(
-        base::Bind(&MojoChannelImpl::OnVersionReady, base::Unretained(this)));
-  }
-
- private:
-  void OnVersionReady(uint32_t unused_version) {
-    holder_->SetInstance(ptr_.get(), ptr_.version());
-  }
-
-  // Owned by ArcBridgeService.
-  ConnectionHolder<InstanceType, HostType>* const holder_;
-
-  // Put as a last member to ensure that any callback tied to the |ptr_|
-  // is not invoked.
-  mojo::InterfacePtr<InstanceType> ptr_;
-
-  DISALLOW_COPY_AND_ASSIGN(MojoChannelImpl);
-};
-
-}  // namespace
-
 ArcBridgeHostImpl::ArcBridgeHostImpl(ArcBridgeService* arc_bridge_service,
                                      mojom::ArcBridgeInstancePtr instance)
     : arc_bridge_service_(arc_bridge_service),
@@ -320,7 +267,7 @@ void ArcBridgeHostImpl::OnInstanceReady(
   // closed on ArcBridgeHost/Instance closing or the ArcBridgeHostImpl's
   // destruction.
   auto* channel =
-      new MojoChannelImpl<InstanceType, HostType>(holder, std::move(ptr));
+      new MojoChannel<InstanceType, HostType>(holder, std::move(ptr));
   mojo_channels_.emplace_back(channel);
 
   // Since |channel| is managed by |mojo_channels_|, its lifetime is shorter
@@ -334,11 +281,11 @@ void ArcBridgeHostImpl::OnInstanceReady(
   channel->QueryVersion();
 }
 
-void ArcBridgeHostImpl::OnChannelClosed(MojoChannel* channel) {
+void ArcBridgeHostImpl::OnChannelClosed(MojoChannelBase* channel) {
   DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
   mojo_channels_.erase(
       std::find_if(mojo_channels_.begin(), mojo_channels_.end(),
-                   [channel](std::unique_ptr<MojoChannel>& ptr) {
+                   [channel](std::unique_ptr<MojoChannelBase>& ptr) {
                      return ptr.get() == channel;
                    }));
 }

components/arc/arc_bridge_host_impl.h

@@ -18,6 +18,7 @@
 namespace arc {
 
 class ArcBridgeService;
+class MojoChannelBase;
 
 // Implementation of the ArcBridgeHost.
 // The lifetime of ArcBridgeHost and ArcBridgeInstance mojo channels are tied
@@ -30,9 +31,6 @@ class ArcBridgeService;
 // Note that ArcBridgeService must be alive while ArcBridgeHostImpl is alive.
 class ArcBridgeHostImpl : public mojom::ArcBridgeHost {
  public:
-  // Interface to keep the Mojo channel InterfacePtr.
-  class MojoChannel;
-
   ArcBridgeHostImpl(ArcBridgeService* arc_bridge_service,
                     mojom::ArcBridgeInstancePtr instance);
   ~ArcBridgeHostImpl() override;
@@ -114,7 +112,7 @@ class ArcBridgeHostImpl : public mojom::ArcBridgeHost {
                        mojo::InterfacePtr<InstanceType> ptr);
 
   // Called if one of the established channels is closed.
-  void OnChannelClosed(MojoChannel* channel);
+  void OnChannelClosed(MojoChannelBase* channel);
 
   THREAD_CHECKER(thread_checker_);
 
@@ -126,7 +124,7 @@ class ArcBridgeHostImpl : public mojom::ArcBridgeHost {
 
   // Put as a last member to ensure that any callback tied to the elements
   // is not invoked.
-  std::vector<std::unique_ptr<MojoChannel>> mojo_channels_;
+  std::vector<std::unique_ptr<MojoChannelBase>> mojo_channels_;
 
   DISALLOW_COPY_AND_ASSIGN(ArcBridgeHostImpl);
 };

components/arc/mojo_channel.h

+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_ARC_MOJO_CHANNEL_H_
+#define COMPONENTS_ARC_MOJO_CHANNEL_H_
+
+#include <utility>
+
+#include "base/bind.h"
+#include "base/macros.h"
+#include "components/arc/connection_holder.h"
+
+namespace arc {
+
+// Thin interface to wrap InterfacePtr<T> with type erasure.
+class MojoChannelBase {
+ public:
+  virtual ~MojoChannelBase() = default;
+
+ protected:
+  MojoChannelBase() = default;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MojoChannelBase);
+};
+
+// Thin wrapper for InterfacePtr<T>, where T is one of ARC mojo Instance class.
+template <typename InstanceType, typename HostType>
+class MojoChannel : public MojoChannelBase {
+ public:
+  MojoChannel(ConnectionHolder<InstanceType, HostType>* holder,
+              mojo::InterfacePtr<InstanceType> ptr)
+      : holder_(holder), ptr_(std::move(ptr)) {
+    // Delay registration to the ConnectionHolder until the version is ready.
+  }
+
+  ~MojoChannel() override { holder_->CloseInstance(ptr_.get()); }
+
+  void set_connection_error_handler(base::OnceClosure error_handler) {
+    ptr_.set_connection_error_handler(std::move(error_handler));
+  }
+
+  void QueryVersion() {
+    // Note: the callback will not be called if |ptr_| is destroyed.
+    ptr_.QueryVersion(
+        base::Bind(&MojoChannel::OnVersionReady, base::Unretained(this)));
+  }
+
+ private:
+  void OnVersionReady(uint32_t unused_version) {
+    holder_->SetInstance(ptr_.get(), ptr_.version());
+  }
+
+  // Externally owned ConnectionHolder instance.
+  ConnectionHolder<InstanceType, HostType>* const holder_;
+
+  // Put as a last member to ensure that any callback tied to the |ptr_|
+  // is not invoked.
+  mojo::InterfacePtr<InstanceType> ptr_;
+
+  DISALLOW_COPY_AND_ASSIGN(MojoChannel);
+};
+
+}  // namespace arc
+
+#endif  // COMPONENTS_ARC_MOJO_CHANNEL_H_