Add length-equality test in String operator== checks.

Change-Id: I6ebc6ef85aac4539269f137c1f29f95b9828d4f9
diff --git a/include/utils/String16.h b/include/utils/String16.h
index 07a0c11..d98b2d04 100644
--- a/include/utils/String16.h
+++ b/include/utils/String16.h
@@ -205,7 +205,9 @@
 
 inline bool String16::operator==(const String16& other) const
 {
-    return strzcmp16(mString, size(), other.mString, other.size()) == 0;
+    const size_t n1 = size();
+    const size_t n2 = other.size();
+    return n1 == n2 && strzcmp16(mString, n1, other.mString, n2) == 0;
 }
 
 inline bool String16::operator!=(const String16& other) const