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 273292)
+++ chrome/browser/media/webrtc_logging_handler_host.h	(working copy)
@@ -11,13 +11,8 @@
 #include "content/public/browser/browser_message_filter.h"
 #include "net/base/net_util.h"
 
-namespace net {
-class URLRequestContextGetter;
-}  // namespace net
-
 class PartialCircularBuffer;
 class Profile;
-class RenderProcessHost;
 
 typedef std::map<std::string, std::string> MetaDataMap;
 
@@ -128,8 +123,9 @@
 
   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_|.
@@ -149,7 +145,7 @@
   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