Allow TracingController to output trace data to specified file

content/public/browser/tracing_controller.h

Index: content/public/browser/tracing_controller.h
diff --git a/content/public/browser/tracing_controller.h b/content/public/browser/tracing_controller.h
index d3bc7bd9df9f2ec6dc5cbd6d305d6dacaec1e070..2434ad4967a2ec64f0ac2a54b763fe13efa20155 100644
--- a/content/public/browser/tracing_controller.h
+++ b/content/public/browser/tracing_controller.h
@@ -75,9 +75,16 @@ class TracingController {
   // Once all child processes have acked to the DisableRecording request,
   // TracingFileResultCallback will be called back with a file that contains
   // the traced data.
-  typedef base::Callback<void(scoped_ptr<base::FilePath>)>
-      TracingFileResultCallback;
-  virtual bool DisableRecording(const TracingFileResultCallback& callback) = 0;
+  //
+  // Trace data will be written into |result_file_path| if it is not empty, or
+  // into a temporary file. The actual file path will be passed to |callback| if
+  // it's not null.
+  //
+  // If |result_file_path| is empty and |callback| is null, trace data won't be
+  // written to any file.
+  typedef base::Callback<void(const base::FilePath&)> TracingFileResultCallback;
+  virtual bool DisableRecording(const base::FilePath& result_file_path,
+                                const TracingFileResultCallback& callback) = 0;
 
   // Start monitoring on all processes.
   //
@@ -119,7 +126,14 @@ class TracingController {
   // Once all child processes have acked to the CaptureMonitoringSnapshot
   // request, TracingFileResultCallback will be called back with a file that
   // contains the traced data.
+  //
+  // Trace data will be written into |result_file_path| if it is not empty, or
+  // into a temporary file. The actual file path will be passed to |callback|.
+  //
+  // If |result_file_path| is empty and |callback| is null, trace data won't be
+  // written to any file.
   virtual void CaptureMonitoringSnapshot(
+      const base::FilePath& result_file_path,
       const TracingFileResultCallback& callback) = 0;
 
  protected: