Add queued_time_ms trace for events in message loop

base/location.h

 // 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.
 
 #ifndef BASE_LOCATION_H_
 #define BASE_LOCATION_H_
 
 #include <string>
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace base {
+namespace debug {
+class ConvertableToTraceFormat;
+}
+}
 
 namespace tracked_objects {
 
 // Location provides basic info where of an object was constructed, or was
 // significantly brought to life.
 class BASE_EXPORT Location {
  public:
   // Constructor should be called with a long-lived char*, such as __FILE__.
   // It assumes the provided value will persist as a global constant, and it
   // will not make a copy of it.
@@ skipping 18 matching lines @@
       return file_name_ < other.file_name_;
     return function_name_ < other.function_name_;
   }
 
   const char* function_name()   const { return function_name_; }
   const char* file_name()       const { return file_name_; }
   int line_number()             const { return line_number_; }
   const void* program_counter() const { return program_counter_; }
 
   std::string ToString() const;
+  scoped_ptr<base::debug::ConvertableToTraceFormat> ToTraceFormat() const;
 
   // Translate the some of the state in this instance into a human readable
   // string with HTML characters in the function names escaped, and append that
   // string to |output|.  Inclusion of the file_name_ and function_name_ are
   // optional, and controlled by the boolean arguments.
   void Write(bool display_filename, bool display_function_name,
              std::string* output) const;
 
   // Write function_name_ in HTML with '<' and '>' properly encoded.
   void WriteFunctionName(std::string* output) const;
@@ skipping 25 matching lines @@
 
 #define FROM_HERE_WITH_EXPLICIT_FUNCTION(function_name)                        \
     ::tracked_objects::Location(function_name,                                 \
                                 __FILE__,                                      \
                                 __LINE__,                                      \
                                 ::tracked_objects::GetProgramCounter())
 
 }  // namespace tracked_objects
 
 #endif  // BASE_LOCATION_H_