[UMA] Use proper C++ objects to serialize tracked_objects across process boundaries.

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"
-
-namespace base {
-class DictionaryValue;
-}
+#include "base/basictypes.h"
 
 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 29 matching lines @@
   // 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;
 
-  // Construct a Value* representation.  The caller assumes ownership of the
-  // memory in the returned instance.
-  base::DictionaryValue* ToValue() const;
-
  private:
   const char* function_name_;
   const char* file_name_;
   int line_number_;
   const void* program_counter_;
 };
 
+// A "snapshotted" representation of the Location class that can safely be
+// passed across process boundaries.
+struct BASE_EXPORT LocationSnapshot {
+  // The default constructor is exposed to support the IPC serialization macros.
+  LocationSnapshot();
+  explicit LocationSnapshot(const tracked_objects::Location& location);
+  ~LocationSnapshot();
+
+  std::string file_name;
+  std::string function_name;
+  int line_number;
+};
+
 BASE_EXPORT const void* GetProgramCounter();
 
 // Define a macro to record the current source location.
 #define FROM_HERE FROM_HERE_WITH_EXPLICIT_FUNCTION(__FUNCTION__)
 
 #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_