Adds mailto: URL support to app launching.

ios/chrome/browser/web/mailto_handler_unittest.mm

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ios/chrome/browser/web/mailto_handler.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+#include "testing/gtest_mac.h"
+
+TEST(MailtoHandlerTest, TestConstructor) {
+  MailtoHandler* handler =
+      [[MailtoHandler alloc] initWithName:@"Some App" appStoreID:@"12345"];
+  EXPECT_NSEQ(@"Some App", [handler appName]);
+  EXPECT_NSEQ(@"12345", [handler appStoreID]);
+}