Fix google-explicit-constructor warnings.

Bug: 28341362
Change-Id: Ief7bba536cca6773b1462b5273a330fa8da2bc51
diff --git a/toStringArray.cpp b/toStringArray.cpp
index f2fa53c..f2b0add 100644
--- a/toStringArray.cpp
+++ b/toStringArray.cpp
@@ -23,7 +23,7 @@
 
 struct ArrayCounter {
     const char* const* strings;
-    ArrayCounter(const char* const* strings) : strings(strings) {}
+    explicit ArrayCounter(const char* const* strings) : strings(strings) {}
     size_t operator()() {
         size_t count = 0;
         while (strings[count] != NULL) {
@@ -35,7 +35,7 @@
 
 struct ArrayGetter {
     const char* const* strings;
-    ArrayGetter(const char* const* strings) : strings(strings) {}
+    explicit ArrayGetter(const char* const* strings) : strings(strings) {}
     const char* operator()(size_t i) {
         return strings[i];
     }