headless: Add support for host resolver mapping

headless/lib/headless_browser_browsertest.cc

Index: headless/lib/headless_browser_browsertest.cc
diff --git a/headless/lib/headless_browser_browsertest.cc b/headless/lib/headless_browser_browsertest.cc
index 9cc594073cef0d6aa78bdb2c4ff4f8c6b55923ad..b53fa24ec27ea572f7a11258a42f2e87e48b5fe6 100644
--- a/headless/lib/headless_browser_browsertest.cc
+++ b/headless/lib/headless_browser_browsertest.cc
@@ -67,4 +67,19 @@ IN_PROC_BROWSER_TEST_F(HeadlessBrowserTestWithProxy, SetProxyServer) {
   EXPECT_TRUE(WaitForLoad(web_contents.get()));
 }
 
+IN_PROC_BROWSER_TEST_F(HeadlessBrowserTest, SetProxyServer) {

[altimin, 2016/04/21 14:35:55]

Nit: maybe we can come up with a better name for this test?
SetHostResolverRules?

[Sami, 2016/04/21 14:58:37]

Hmm, not a bad idea :D

+  EXPECT_TRUE(embedded_test_server()->Start());
+  HeadlessBrowser::Options::Builder builder;
+  builder.SetHostResolverRules("MAP not-an-actual-domain.tld 127.0.0.1");
+  SetBrowserOptions(builder.Build());
+
+  // Load a page which doesn't actually exist, but which is turned into a valid
+  // address by our host resolver rules.
+  std::unique_ptr<HeadlessWebContents> web_contents =
+      browser()->CreateWebContents(
+          GURL("http://not-an-actual-domain.tld/hello.html"),
+          gfx::Size(800, 600));
+  EXPECT_TRUE(WaitForLoad(web_contents.get()));
+}
+
 }  // namespace headless