[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 fc9d3603251a27f526f599e564714ec3bb5befbc..a536602eedd0c28e15b80bb32d71183abe89c885 100644
--- a/base/location.h
+++ b/base/location.h
@@ -8,10 +8,7 @@
 #include <string>
 
 #include "base/base_export.h"
-
-namespace base {
-class DictionaryValue;
-}
+#include "base/basictypes.h"
 
 namespace tracked_objects {
 
@@ -61,10 +58,6 @@ 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_;
@@ -72,6 +65,19 @@ 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();
+  explicit SerializedLocation(const tracked_objects::Location& location);
+  ~SerializedLocation();
+
+  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.