Revised CL for customisable logging (replacing printfs).

runtime/bin/dbg_connection_macos.cc

Index: runtime/bin/dbg_connection_macos.cc
===================================================================
--- runtime/bin/dbg_connection_macos.cc	(revision 14903)
+++ runtime/bin/dbg_connection_macos.cc	(working copy)
@@ -12,6 +12,7 @@
 #include "bin/dartutils.h"
 #include "bin/dbg_connection.h"
 #include "bin/fdutils.h"
+#include "bin/log.h"
 #include "bin/socket.h"
 #include "platform/thread.h"
 #include "platform/utils.h"
@@ -87,10 +88,10 @@
   } else if (ident == wakeup_fds_[0]) {
     Message msg;
     if (ReceiveMessage(&msg)) {
-      printf("Received sync message id %d.\n", msg.msg_id);
+      Log::Print("Received sync message id %d.\n", msg.msg_id);
     }
   } else {
-    printf("unexpected: receiving debugger connection event.\n");
+    Log::Print("unexpected: receiving debugger connection event.\n");
     UNIMPLEMENTED();
   }
 }
@@ -113,7 +114,7 @@
       }
     }
   }
-  printf("shutting down debugger thread\n");
+  Log::Print("shutting down debugger thread\n");
 }