Log device/usb messages to chrome://device-log.

components/device_event_log/device_event_log.h

 // 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.
 
 #ifndef COMPONENTS_DEVICE_EVENT_LOG_DEVICE_EVENT_LOG_H_
 #define COMPONENTS_DEVICE_EVENT_LOG_DEVICE_EVENT_LOG_H_
 
 #include <cstring>
 #include <sstream>
 
@@ skipping 13 matching lines @@
 
 #define NET_LOG(level)                             \
   DEVICE_LOG(::device_event_log::LOG_TYPE_NETWORK, \
              ::device_event_log::LOG_LEVEL_##level)
 #define POWER_LOG(level)                         \
   DEVICE_LOG(::device_event_log::LOG_TYPE_POWER, \
              ::device_event_log::LOG_LEVEL_##level)
 #define LOGIN_LOG(level)                         \
   DEVICE_LOG(::device_event_log::LOG_TYPE_LOGIN, \
              ::device_event_log::LOG_LEVEL_##level)
+#define USB_LOG(level)                         \
+  DEVICE_LOG(::device_event_log::LOG_TYPE_USB, \
+             ::device_event_log::LOG_LEVEL_##level)
 
 // Generally prefer the above macros unless |type| or  |level| is not constant.
 
 #define DEVICE_LOG(type, level)                                            \
   ::device_event_log::internal::DeviceEventLogInstance(__FILE__, __LINE__, \
                                                        type, level).stream()
 
 // Declare {Type_LOG_IF_SLOW() at the top of a method to log slow methods
 // where "slow" is defined by kSlowMethodThresholdMs in the .cc file.
 #define SCOPED_NET_LOG_IF_SLOW() \
@@ skipping 10 matching lines @@
 // Used to specify the type of event. NOTE: Be sure to update LogTypeFromString
 // and GetLogTypeString when adding entries to this enum. Also consider
 // updating chrome://device-log (see device_log_ui.cc).
 enum LogType {
   // Shill / network configuration related events.
   LOG_TYPE_NETWORK,
   // Power manager related events.
   LOG_TYPE_POWER,
   // Login related events.
   LOG_TYPE_LOGIN,
+  // USB device related events (i.e. device/usb).
+  LOG_TYPE_USB,
   // Used internally
   LOG_TYPE_UNKNOWN
 };
 
 // Used to specify the detail level for logging. In GetAsString, used to
 // specify the maximum detail level (i.e. EVENT will include USER and ERROR).
 // See top-level comment for guidelines for each type.
 enum LogLevel {
   LOG_LEVEL_ERROR = 0,
   LOG_LEVEL_USER = 1,
@@ skipping 92 matching lines @@
   LogType type_;
   std::string name_;
   base::ElapsedTimer timer_;
 };
 
 }  // namespace internal
 
 }  // namespace device_event_log
 
 #endif  // DEVICE_EVENT_LOG_DEVICE_EVENT_LOG_H_