arc: enable Android tracing from chrome://tracing in dev mode

components/arc/arc_bridge_host_impl.cc

 // Copyright 2016 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.
 
 #include "components/arc/arc_bridge_host_impl.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 180 matching lines @@
     mojom::ProcessInstancePtr process_ptr) {
   OnInstanceReady(arc_bridge_service_->process(), std::move(process_ptr));
 }
 
 void ArcBridgeHostImpl::OnStorageManagerInstanceReady(
     mojom::StorageManagerInstancePtr storage_manager_ptr) {
   OnInstanceReady(arc_bridge_service_->storage_manager(),
                   std::move(storage_manager_ptr));
 }
 
+void ArcBridgeHostImpl::OnTracingInstanceReady(
+    mojom::TracingInstancePtr tracing_ptr) {
+  OnInstanceReady(arc_bridge_service_->tracing(), std::move(tracing_ptr));
+}
+
 void ArcBridgeHostImpl::OnTtsInstanceReady(mojom::TtsInstancePtr tts_ptr) {
   OnInstanceReady(arc_bridge_service_->tts(), std::move(tts_ptr));
 }
 
 void ArcBridgeHostImpl::OnVideoInstanceReady(
     mojom::VideoInstancePtr video_ptr) {
   OnInstanceReady(arc_bridge_service_->video(), std::move(video_ptr));
 }
 
 void ArcBridgeHostImpl::OnWallpaperInstanceReady(
@@ skipping 39 matching lines @@
 void ArcBridgeHostImpl::OnChannelClosed(MojoChannel* channel) {
   DCHECK(thread_checker_.CalledOnValidThread());
   mojo_channels_.erase(
       std::find_if(mojo_channels_.begin(), mojo_channels_.end(),
                    [channel](std::unique_ptr<MojoChannel>& ptr) {
                      return ptr.get() == channel;
                    }));
 }
 
 }  // namespace arc