Changed monitor to contain method and return pc values for logging.

The monitor saves method and return pc for logging, instead of the
source filename and line number. This saves it from having to do a
lookup every time a fat lock is acquired.

Change-Id: I88871abc90626b9e4dffc9677c093fd24937385c
diff --git a/src/thread.h b/src/thread.h
index 15ded24..7b8c8b9 100644
--- a/src/thread.h
+++ b/src/thread.h
@@ -229,9 +229,6 @@
   // Returns the java.lang.Thread's name, or NULL.
   String* GetName() const;
 
-  // Returns the current method's declaring class' source file and the current line number.
-  void GetCurrentLocation(const char*& source_file, uint32_t& line_number) const;
-
   Object* GetPeer() const {
     return peer_;
   }
@@ -244,6 +241,8 @@
   // This is used by the JNI implementation for logging and diagnostic purposes.
   const Method* GetCurrentMethod() const;
 
+  uint32_t GetCurrentReturnPc() const;
+
   bool IsExceptionPending() const {
     return exception_ != NULL;
   }