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

components/device_event_log/device_event_log_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/device_event_log/device_event_log_impl.h"
 
 #include <cmath>
 #include <list>
 #include <set>
 
@@ skipping 11 matching lines @@
 
 namespace device_event_log {
 
 namespace {
 
 const char* kLogLevelName[] = {"Error", "User", "Event", "Debug"};
 
 const char* kLogTypeNetworkDesc = "Network";
 const char* kLogTypePowerDesc = "Power";
 const char* kLogTypeLoginDesc = "Login";
+const char* kLogTypeUsbDesc = "USB";
 
 std::string GetLogTypeString(LogType type) {
-  if (type == LOG_TYPE_NETWORK)
-    return kLogTypeNetworkDesc;
-  if (type == LOG_TYPE_POWER)
-    return kLogTypePowerDesc;
-  if (type == LOG_TYPE_LOGIN)
-    return kLogTypeLoginDesc;
-  NOTREACHED();
-  return "Unknown";
+  switch (type) {
+    case LOG_TYPE_NETWORK:
+      return kLogTypeNetworkDesc;
+    case LOG_TYPE_POWER:
+      return kLogTypePowerDesc;
+    case LOG_TYPE_LOGIN:
+      return kLogTypeLoginDesc;
+    case LOG_TYPE_USB:
+      return kLogTypeUsbDesc;
+    default:
+      NOTREACHED();
+      return "Unknown";
+  }
 }
 
 std::string DateAndTimeWithMicroseconds(const base::Time& time) {
   base::Time::Exploded exploded;
   time.LocalExplode(&exploded);
   // base::Time::Exploded does not include microseconds, but sometimes we need
   // microseconds, so append '.' + usecs to the end of the formatted string.
   int usecs = static_cast<int>(fmod(time.ToDoubleT() * 1000000, 1000000));
   return base::StringPrintf("%04d/%02d/%02d %02d:%02d:%02d.%06d", exploded.year,
                             exploded.month, exploded.day_of_month,
@@ skipping 340 matching lines @@
   if (filedesc) {
     file = filedesc;
     size_t last_slash_pos = file.find_last_of("\\/");
     if (last_slash_pos != std::string::npos) {
       file.erase(0, last_slash_pos + 1);
     }
   }
 }
 
 }  // namespace device_event_log