Log errors from libusb.

components/usb_service/usb_device_impl.cc

 // Copyright 2014 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/usb_service/usb_device_impl.h"
 
 #include <algorithm>
 
 #include "base/stl_util.h"
 #include "components/usb_service/usb_context.h"
 #include "components/usb_service/usb_device_handle_impl.h"
+#include "components/usb_service/usb_error.h"
 #include "components/usb_service/usb_interface_impl.h"
 #include "content/public/browser/browser_thread.h"
 #include "third_party/libusb/src/libusb/libusb.h"
 
 #if defined(OS_CHROMEOS)
 #include "base/sys_info.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/permission_broker_client.h"
 #endif  // defined(OS_CHROMEOS)
 
@@ skipping 64 matching lines @@
                    interface_id,
                    base::Bind(&OnRequestUsbAccessReplied, callback)));
   }
 }
 
 #endif
 
 scoped_refptr<UsbDeviceHandle> UsbDeviceImpl::Open() {
   DCHECK(thread_checker_.CalledOnValidThread());
   PlatformUsbDeviceHandle handle;
-  int rv = libusb_open(platform_device_, &handle);
+  const int rv = libusb_open(platform_device_, &handle);
   if (LIBUSB_SUCCESS == rv) {
     scoped_refptr<UsbConfigDescriptor> interfaces = ListInterfaces();
     if (!interfaces)
       return NULL;
     scoped_refptr<UsbDeviceHandleImpl> device_handle =
         new UsbDeviceHandleImpl(context_, this, handle, interfaces);
     handles_.push_back(device_handle);
     return device_handle;
+  } else {
+    LOG(ERROR) << "Failed to open device: " << ConvertErrorToString(rv);
+    return NULL;
   }
-  return NULL;
 }
 
 bool UsbDeviceImpl::Close(scoped_refptr<UsbDeviceHandle> handle) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   for (HandlesVector::iterator it = handles_.begin(); it != handles_.end();
        ++it) {
     if (*it == handle) {
       (*it)->InternalClose();
       handles_.erase(it);
       return true;
     }
   }
   return false;
 }
 
 scoped_refptr<UsbConfigDescriptor> UsbDeviceImpl::ListInterfaces() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   PlatformUsbConfigDescriptor platform_config;
-  const int list_result =
+  const int rv =
       libusb_get_active_config_descriptor(platform_device_, &platform_config);
-  if (list_result == 0)
+  if (rv == LIBUSB_SUCCESS) {
     return new UsbConfigDescriptorImpl(platform_config);
-
-  return NULL;
+  } else {
+    LOG(ERROR) << "Failed to get config descriptor: "
+        << ConvertErrorToString(rv);
+    return NULL;
+  }
 }
 
 void UsbDeviceImpl::OnDisconnect() {
   DCHECK(thread_checker_.CalledOnValidThread());
   HandlesVector handles;
   swap(handles, handles_);
   for (HandlesVector::iterator it = handles.begin(); it != handles.end(); ++it)
     (*it)->InternalClose();
 }
 
 }  // namespace usb_service