Initialize SubstringSetMatcher on construction

chrome/browser/extensions/api/declarative/substring_set_matcher_unittest.cc

Index: chrome/browser/extensions/api/declarative/substring_set_matcher_unittest.cc
diff --git a/chrome/browser/extensions/api/declarative/substring_set_matcher_unittest.cc b/chrome/browser/extensions/api/declarative/substring_set_matcher_unittest.cc
index d18ba36e6b9a5ff61ebab33dba07d73a113f6877..0e8ce50c64d349771594499583069758579b3a6f 100644
--- a/chrome/browser/extensions/api/declarative/substring_set_matcher_unittest.cc
+++ b/chrome/browser/extensions/api/declarative/substring_set_matcher_unittest.cc
@@ -164,3 +164,10 @@ TEST(SubstringSetMatcherTest, RegisterAndRemove) {
   EXPECT_TRUE(matches.end() != matches.find(1));
   EXPECT_TRUE(matches.end() == matches.find(2));
 }
+
+TEST(SubstringSetMatcherTest, TestEmptyMatcher) {
+  SubstringSetMatcher matcher;
+  std::set<int> matches;
+  matcher.Match("abd", &matches);
+  EXPECT_TRUE(matches.empty());
+}