Remove debug log message from web_usb_client_impl.cc.

content/renderer/usb/web_usb_client_impl.cc

 // Copyright 2015 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 "content/renderer/usb/web_usb_client_impl.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/move.h"
@@ skipping 50 matching lines @@
     (*devices)[i] = new WebUSBDeviceImpl(
         device.Pass(), mojo::ConvertTo<blink::WebUSBDeviceInfo>(results[i]));
   }
   scoped_callbacks.PassCallbacks()->onSuccess(blink::adoptWebPtr(devices));
 }
 
 }  // namespace
 
 WebUSBClientImpl::WebUSBClientImpl(content::ServiceRegistry* service_registry) {
   service_registry->ConnectToRemoteService(mojo::GetProxy(&device_manager_));
-  device_manager_.set_connection_error_handler(
-      [this]() { LOG(ERROR) << "Device manager connection failed."; });
 }
 
 WebUSBClientImpl::~WebUSBClientImpl() {}
 
 void WebUSBClientImpl::getDevices(
     blink::WebUSBClientGetDevicesCallbacks* callbacks) {
   auto scoped_callbacks = MakeScopedUSBCallbacks(callbacks);
   device_manager_->GetDevices(
       nullptr,
       base::Bind(&OnGetDevicesComplete, base::Passed(&scoped_callbacks),
@@ skipping 39 matching lines @@
     const device::usb::DeviceInfoPtr& device_info =
         notification->devices_removed[i];
     device::usb::DevicePtr device;
     device_manager_->GetDevice(device_info->guid, mojo::GetProxy(&device));
     observer_->onDeviceDisconnected(blink::adoptWebPtr(new WebUSBDeviceImpl(
         device.Pass(), mojo::ConvertTo<blink::WebUSBDeviceInfo>(device_info))));
   }
 }
 
 }  // namespace content