Fix memory leak in TraceSubscriberStdioImpl.

content/browser/trace_subscriber_stdio.cc

 // Copyright (c) 2012 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 "content/browser/trace_subscriber_stdio.h"
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/threading/sequenced_worker_pool.h"
@@ skipping 40 matching lines @@
 
   bool IsValid() {
     return file_ && (0 == ferror(file_));
   }
 
   void CloseFile() {
     if (file_) {
       fclose(file_);
       file_ = 0;
     }
+    // This is important, as it breaks a reference cycle.
+    trace_buffer_.SetOutputCallback(
+        base::debug::TraceResultBuffer::OutputCallback());
   }
 
   void Write(const std::string& output_str) {
     if (IsValid()) {
       size_t written = fwrite(output_str.data(), 1, output_str.size(), file_);
       if (written != output_str.size()) {
         LOG(ERROR) << "Error " << ferror(file_) << " in fwrite() to trace file";
         CloseFile();
       }
     }
   }
 
   FilePath path_;
   FILE* file_;
   base::debug::TraceResultBuffer trace_buffer_;
 };
 
 TraceSubscriberStdio::TraceSubscriberStdio(const FilePath& path)
     : impl_(new TraceSubscriberStdioImpl(path)) {
   BrowserThread::PostBlockingPoolSequencedTask(
       __FILE__, FROM_HERE,
-      base::Bind(&TraceSubscriberStdioImpl::OnStart, impl_.get()));
+      base::Bind(&TraceSubscriberStdioImpl::OnStart, impl_));
 }
 
 TraceSubscriberStdio::~TraceSubscriberStdio() {
 }
 
 void TraceSubscriberStdio::OnEndTracingComplete() {
   BrowserThread::PostBlockingPoolSequencedTask(
       __FILE__, FROM_HERE,
-      base::Bind(&TraceSubscriberStdioImpl::OnEnd, impl_.get()));
+      base::Bind(&TraceSubscriberStdioImpl::OnEnd, impl_));
 }
 
 void TraceSubscriberStdio::OnTraceDataCollected(
     const scoped_refptr<base::RefCountedString>& data_ptr) {
   BrowserThread::PostBlockingPoolSequencedTask(
       __FILE__, FROM_HERE,
-      base::Bind(&TraceSubscriberStdioImpl::OnData, impl_.get(), data_ptr));
+      base::Bind(&TraceSubscriberStdioImpl::OnData, impl_, data_ptr));
 }
 
 }  // namespace content