Convert WebRtcLoggingHandlerHost to use the blocking thread pool.

chrome/browser/media/webrtc_logging_handler_host.h

Index: chrome/browser/media/webrtc_logging_handler_host.h
===================================================================
--- chrome/browser/media/webrtc_logging_handler_host.h	(revision 274367)
+++ chrome/browser/media/webrtc_logging_handler_host.h	(working copy)
@@ -14,10 +14,6 @@
 #include "content/public/browser/render_process_host.h"
 #include "net/base/net_util.h"
 
-namespace net {
-class URLRequestContextGetter;
-}  // namespace net
-
 class PartialCircularBuffer;
 class Profile;
 
@@ -136,8 +132,9 @@
 
   void StartLoggingIfAllowed();
   void DoStartLogging();
-  void LogInitialInfoOnFileThread();
-  void LogInitialInfoOnIOThread(const net::NetworkInterfaceList& network_list);
+  void LogInitialInfoOnBlockingPool();
+  void LogInitialInfoOnIOThread(const net::NetworkInterfaceList& network_list,
+                                const std::string& linux_distro);
   void NotifyLoggingStarted();
 
   // Writes a formatted log |message| to the |circular_buffer_|.
@@ -176,7 +173,7 @@
   scoped_ptr<PartialCircularBuffer> circular_buffer_;
 
   // The profile associated with our renderer process.
-  Profile* profile_;
+  const Profile* const profile_;
 
   // These are only accessed on the IO thread, except when in STARTING state. In
   // this state we are protected since entering any function that alters the