Remove obsolete DCHECK for empty HTTPS alias names

Empty alias name has been parsable and allowed since the update to
draft-ietf-dnsop-svcb-https-01.

Fixed: 1145098
Bug: 1138620
Change-Id: I980365204c1b997335c781567e62c7fcdf3094e2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2517627
Commit-Queue: Eric Orth <ericorth@chromium.org>
Commit-Queue: Dan McArdle <dmcardle@chromium.org>
Auto-Submit: Eric Orth <ericorth@chromium.org>
Reviewed-by: Dan McArdle <dmcardle@chromium.org>
Cr-Commit-Position: refs/heads/master@{#823644}

net/dns/https_record_rdata.cc

@@ -175,9 +175,7 @@ const ServiceFormHttpsRecordRdata* HttpsRecordRdata::AsServiceForm() const {
 }
 
 AliasFormHttpsRecordRdata::AliasFormHttpsRecordRdata(std::string alias_name)
-    : alias_name_(std::move(alias_name)) {
-  DCHECK(!alias_name_.empty());
-}
+    : alias_name_(std::move(alias_name)) {}
 
 // static
 std::unique_ptr<AliasFormHttpsRecordRdata> AliasFormHttpsRecordRdata::Parse(

net/dns/https_record_rdata_unittest.cc

@@ -37,6 +37,26 @@ TEST(HttpsRecordRdataTest, ParsesAlias) {
   EXPECT_EQ(alias_rdata->alias_name(), "chromium.org");
 }
 
+TEST(HttpsRecordRdataTest, ParseAliasWithEmptyName) {
+  const char kRdata[] =
+      // Priority: 0 for alias record
+      "\000\000"
+      // Alias name: ""
+      "\000";
+
+  std::unique_ptr<HttpsRecordRdata> rdata =
+      HttpsRecordRdata::Parse(base::StringPiece(kRdata, sizeof(kRdata) - 1));
+  ASSERT_TRUE(rdata);
+
+  AliasFormHttpsRecordRdata expected("");
+  EXPECT_TRUE(rdata->IsEqual(&expected));
+
+  EXPECT_TRUE(rdata->IsAlias());
+  AliasFormHttpsRecordRdata* alias_rdata = rdata->AsAliasForm();
+  ASSERT_TRUE(alias_rdata);
+  EXPECT_TRUE(alias_rdata->alias_name().empty());
+}
+
 TEST(HttpsRecordRdataTest, IgnoreAliasParams) {
   const char kRdata[] =
       // Priority: 0 for alias record