Declarative resource hints go through mojo IPC to //content

content/browser/loader/resource_hints_browsertest.cc

+// Copyright 2016 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 <algorithm>
+
+#include "content/public/test/browser_test_utils.h"
+#include "content/public/test/content_browser_test.h"
+#include "content/public/test/content_browser_test_utils.h"
+#include "content/shell/browser/shell.h"
+#include "net/dns/host_resolver_proc.h"
+#include "net/dns/mock_host_resolver.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace content {
+
+class MockHostResolverProc : public net::HostResolverProc {
+ public:
+  MockHostResolverProc() : net::HostResolverProc(nullptr) {}
+
+  int Resolve(const std::string& host,
+              net::AddressFamily address_family,
+              net::HostResolverFlags flags,
+              net::AddressList* addresses,
+              int* os_error) override {
+    requests_.push_back(host);
+    return 0;
+  }
+
+  size_t num_requests() { return requests_.size(); }
+
+  bool host_requested(std::string host) {
+    return std::find(requests_.begin(), requests_.end(), host) !=
+           requests_.end();
+  }
+
+ private:
+  ~MockHostResolverProc() override {}
+
+  std::vector<std::string> requests_;
+};
+
+class ResourceHintsBrowserTest : public ContentBrowserTest {
+ public:
+  ResourceHintsBrowserTest()
+      : mock_host_resolver_proc_(new MockHostResolverProc),
+        scoped_host_resolver_proc_(nullptr) {}
+
+ protected:
+  scoped_refptr<MockHostResolverProc> mock_host_resolver_proc_;
+  std::unique_ptr<net::ScopedDefaultHostResolverProc>
+      scoped_host_resolver_proc_;
+};
+
+IN_PROC_BROWSER_TEST_F(ResourceHintsBrowserTest, DnsPrefetch) {
+  scoped_host_resolver_proc_.reset(
+      new net::ScopedDefaultHostResolverProc(mock_host_resolver_proc_.get()));
+  ASSERT_TRUE(embedded_test_server()->Start());
+
+  EXPECT_TRUE(NavigateToURL(shell(), embedded_test_server()->GetURL(
+                                         "/resource_hints/dns_prefetch.html")));
+  EXPECT_TRUE(
+      NavigateToURL(shell(), embedded_test_server()->GetURL("/title1.html")));
+
+  EXPECT_EQ(mock_host_resolver_proc_->num_requests(), 1u);
+  EXPECT_TRUE(mock_host_resolver_proc_->host_requested("chromium.org"));
+  scoped_host_resolver_proc_.reset();
+}
+
+IN_PROC_BROWSER_TEST_F(ResourceHintsBrowserTest, DnsPrefetchMany) {
+  scoped_host_resolver_proc_.reset(
+      new net::ScopedDefaultHostResolverProc(mock_host_resolver_proc_.get()));
+  ASSERT_TRUE(embedded_test_server()->Start());
+
+  EXPECT_TRUE(
+      NavigateToURL(shell(), embedded_test_server()->GetURL(
+                                 "/resource_hints/dns_prefetch_many.html")));
+  EXPECT_TRUE(
+      NavigateToURL(shell(), embedded_test_server()->GetURL("/title1.html")));
+
+  EXPECT_EQ(mock_host_resolver_proc_->num_requests(), 4u);
+  EXPECT_TRUE(mock_host_resolver_proc_->host_requested("chromium1.org"));
+  EXPECT_TRUE(mock_host_resolver_proc_->host_requested("chromium2.org"));
+  EXPECT_TRUE(mock_host_resolver_proc_->host_requested("chromium3.org"));
+  EXPECT_TRUE(mock_host_resolver_proc_->host_requested("chromium4.org"));
+  scoped_host_resolver_proc_.reset();
+}
+
+}  // namespace content