Move stringpiece.h and stringprintf.h to base/.

Change-Id: I7f71b4a12f99c5f81771146c66629ae5a947b229
diff --git a/src/common_test.h b/src/common_test.h
index 60f665a..2836706 100644
--- a/src/common_test.h
+++ b/src/common_test.h
@@ -23,6 +23,7 @@
 #include "../../external/icu4c/common/unicode/uvernum.h"
 #include "base/macros.h"
 #include "base/stl_util.h"
+#include "base/stringprintf.h"
 #include "base/unix_file/fd_file.h"
 #include "class_linker.h"
 #include "class_loader.h"
@@ -35,9 +36,8 @@
 #include "object_utils.h"
 #include "os.h"
 #include "runtime.h"
-#include "ScopedLocalRef.h"
 #include "scoped_thread_state_change.h"
-#include "stringprintf.h"
+#include "ScopedLocalRef.h"
 #include "thread.h"
 #include "UniquePtr.h"
 #include "well_known_classes.h"