[logging] Remove unused code

This removes unused mutex, headers from log.(h|cc).

Change-Id: Ie4dc69a7efa9494b21ff6e2b19828bd740e3a47c
Reviewed-on: https://chromium-review.googlesource.com/1041967Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52946}

src/log-utils.cc

@@ -82,8 +82,7 @@ FILE* Log::Close() {
   return result;
 }
 
-Log::MessageBuilder::MessageBuilder(Log* log)
-    : log_(log), lock_guard_(&log_->mutex_) {
+Log::MessageBuilder::MessageBuilder(Log* log) : log_(log) {
   DCHECK_NOT_NULL(log_->format_buffer_);
 }
 

src/log-utils.h

@@ -7,11 +7,6 @@
 
 #include <stdio.h>
 
-#include <cstdarg>
-
-#include "src/allocation.h"
-#include "src/base/compiler-specific.h"
-#include "src/base/platform/mutex.h"
 #include "src/flags.h"
 #include "src/ostreams.h"
 
@@ -95,7 +90,6 @@ class Log {
 
    private:
     Log* log_;
-    base::LockGuard<base::Mutex> lock_guard_;
   };
 
  private:
@@ -117,10 +111,6 @@ class Log {
   FILE* output_handle_;
   OFStream os_;
 
-  // mutex_ is a Mutex used for enforcing exclusive
-  // access to the formatting buffer and the log file or log memory buffer.
-  base::Mutex mutex_;
-
   // Buffer used for formatting log messages. This is a singleton buffer and
   // mutex_ should be acquired before using it.
   char* format_buffer_;