Remove various bits of lint.

Change-Id: I5f8f61766d2add7fd7ff40d463ea03cb20515988
diff --git a/src/object_utils.h b/src/object_utils.h
index 3af7007..e2d9b88 100644
--- a/src/object_utils.h
+++ b/src/object_utils.h
@@ -232,7 +232,7 @@
 class FieldHelper {
  public:
   FieldHelper() : class_linker_(NULL), dex_cache_(NULL), dex_file_(NULL), field_(NULL) {}
-  FieldHelper(const Field* f) : class_linker_(NULL), dex_cache_(NULL), dex_file_(NULL), field_(f) {}
+  explicit FieldHelper(const Field* f) : class_linker_(NULL), dex_cache_(NULL), dex_file_(NULL), field_(f) {}
   FieldHelper(const Field* f, ClassLinker* l) : class_linker_(l), dex_cache_(NULL), dex_file_(NULL),
       field_(f) {}
 
@@ -370,7 +370,7 @@
  public:
   MethodHelper() : class_linker_(NULL), dex_cache_(NULL), dex_file_(NULL), method_(NULL),
       shorty_(NULL), shorty_len_(0) {}
-  MethodHelper(const Method* m) : class_linker_(NULL), dex_cache_(NULL), dex_file_(NULL),
+  explicit MethodHelper(const Method* m) : class_linker_(NULL), dex_cache_(NULL), dex_file_(NULL),
       method_(NULL), shorty_(NULL), shorty_len_(0) {
     SetMethod(m);
   }