[ad-tagging] Persist IsAdResource across redirects

Bug: 827519
Change-Id: I395dcad4993ecad65ecf7b55d76e7004fc919d3c
Reviewed-on: https://chromium-review.googlesource.com/987915Reviewed-by: Josh Karlin <jkarlin@chromium.org>
Reviewed-by: Nate Chapin <japhet@chromium.org>
Commit-Queue: Charlie Harrison <csharrison@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548638}

third_party/WebKit/Source/platform/loader/fetch/ResourceRequest.cpp

@@ -165,6 +165,8 @@ std::unique_ptr<ResourceRequest> ResourceRequest::CreateRedirectRequest(
   request->SetCheckForBrowserSideNavigation(CheckForBrowserSideNavigation());
   request->SetWasDiscarded(WasDiscarded());
   request->SetCORSPreflightPolicy(CORSPreflightPolicy());
+  if (IsAdResource())
+    request->SetIsAdResource();
 
   return request;
 }

third_party/WebKit/Source/platform/loader/fetch/ResourceRequestTest.cpp

@@ -148,6 +148,14 @@ TEST(ResourceRequestTest, SetIsAdResource) {
   EXPECT_FALSE(original.IsAdResource());
   original.SetIsAdResource();
   EXPECT_TRUE(original.IsAdResource());
+
+  // Should persist across redirects.
+  std::unique_ptr<ResourceRequest> redirect_request =
+      original.CreateRedirectRequest(
+          KURL("https://example.test/redirect"), original.HttpMethod(),
+          original.SiteForCookies(), original.HttpReferrer(),
+          original.GetReferrerPolicy(), original.GetSkipServiceWorker());
+  EXPECT_TRUE(redirect_request->IsAdResource());
 }
 
 }  // namespace blink