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

base/location.h

Index: base/location.h
diff --git a/base/location.h b/base/location.h
index 2fbe62cde82dbd737cc3aa44c4faad400080d54d..34c88eff9203882a150bf0ef3cdaa9f934edac98 100644
--- a/base/location.h
+++ b/base/location.h
@@ -10,6 +10,10 @@
 #include "base/base_export.h"
 #include "base/values.h"
 
+namespace base {
+class DictionaryValue;
+}
+
 namespace tracked_objects {
 
 // Location provides basic info where of an object was constructed, or was
@@ -58,10 +62,6 @@ class BASE_EXPORT Location {
   // 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_;
@@ -69,6 +69,22 @@ class BASE_EXPORT Location {
   const void* program_counter_;
 };
 
+// Serialized representation of the Location class that can safely be passed
+// across process boundaries.
+struct BASE_EXPORT SerializedLocation {
+  // The default constructor is exposed to support the IPC serialization macros.
+  SerializedLocation();
+  SerializedLocation(const tracked_objects::Location& location);
+  ~SerializedLocation();
+
+  // Writes the serialized data into the passed |dictionary|.
+  void ToValue(base::DictionaryValue* dictionary) const;
+
+  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.