[AdTagging] Track resources loaded from memory cache

Requests served from memory cache don't have the is_ad bit in their newly
minted ResourceRequests. The bit is needed by the AdTracker class that
receives a probe on WillSendRequest. This CL copies the bit over to the
new request and tests it.

Bug: 807640
Change-Id: I9656446be52eb19159a84c26cbdf47905a0e1989
Reviewed-on: https://chromium-review.googlesource.com/980700Reviewed-by: Nate Chapin <japhet@chromium.org>
Commit-Queue: Josh Karlin <jkarlin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#546166}

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

@@ -384,6 +384,9 @@ void ResourceFetcher::DidLoadResourceFromMemoryCache(
   resource_request.SetFrameType(original_resource_request.GetFrameType());
   resource_request.SetRequestContext(
       original_resource_request.GetRequestContext());
+  if (original_resource_request.IsAdResource())
+    resource_request.SetIsAdResource();
+
   Context().DispatchDidLoadResourceFromMemoryCache(identifier, resource_request,
                                                    resource->GetResponse());
   Context().DispatchWillSendRequest(

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

@@ -56,6 +56,7 @@
 #include "platform/testing/weburl_loader_mock_factory_impl.h"
 #include "platform/weborigin/KURL.h"
 #include "platform/wtf/Allocator.h"
+#include "platform/wtf/Optional.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebURLLoader.h"
 #include "public/platform/WebURLLoaderMockFactory.h"
@@ -148,6 +149,39 @@ TEST_F(ResourceFetcherTest, UseExistingResource) {
   EXPECT_EQ(resource, new_resource);
 }
 
+// Verify that the ad bit is copied to WillSendRequest's request when the
+// response is served from the memory cache.
+TEST_F(ResourceFetcherTest, WillSendRequestAdBit) {
+  // Add a resource to the memory cache.
+  scoped_refptr<const SecurityOrigin> source_origin =
+      SecurityOrigin::CreateUnique();
+  Context()->SetSecurityOrigin(source_origin);
+  KURL url("http://127.0.0.1:8000/foo.html");
+  Resource* resource = RawResource::CreateForTest(url, Resource::kRaw);
+  AddResourceToMemoryCache(resource, source_origin);
+  ResourceResponse response(url);
+  response.SetHTTPStatusCode(200);
+  response.SetHTTPHeaderField(HTTPNames::Cache_Control, "max-age=3600");
+  resource->ResponseReceived(response, nullptr);
+  resource->FinishForTest();
+
+  // Fetch the cached resource. The request to DispatchWillSendRequest should
+  // preserve the ad bit.
+  ResourceFetcher* fetcher = ResourceFetcher::Create(Context());
+  ResourceRequest resource_request(url);
+  resource_request.SetIsAdResource();
+  resource_request.SetRequestContext(WebURLRequest::kRequestContextInternal);
+  FetchParameters fetch_params(resource_request);
+  platform_->GetURLLoaderMockFactory()->RegisterURL(url, WebURLResponse(), "");
+  Resource* new_resource = RawResource::Fetch(fetch_params, fetcher, nullptr);
+
+  EXPECT_EQ(resource, new_resource);
+  WTF::Optional<ResourceRequest> new_request =
+      Context()->RequestFromWillSendRequest();
+  EXPECT_TRUE(new_request.has_value());
+  EXPECT_TRUE(new_request.value().IsAdResource());
+}
+
 TEST_F(ResourceFetcherTest, Vary) {
   scoped_refptr<const SecurityOrigin> source_origin =
       SecurityOrigin::CreateUnique();

third_party/WebKit/Source/platform/loader/testing/MockFetchContext.h

@@ -12,6 +12,7 @@
 #include "platform/loader/fetch/ResourceTimingInfo.h"
 #include "platform/scheduler/test/fake_frame_scheduler.h"
 #include "platform/scheduler/test/fake_task_runner.h"
+#include "platform/wtf/Optional.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebURLLoaderFactory.h"
 
@@ -49,7 +50,20 @@ class MockFetchContext : public FetchContext {
     security_origin_ = security_origin;
   }
 
+  // The last ResourceRequest passed to DispatchWillSendRequest.
+  WTF::Optional<ResourceRequest> RequestFromWillSendRequest() const {
+    return will_send_request_;
+  }
+
   // FetchContext:
+  void DispatchWillSendRequest(
+      unsigned long identifier,
+      ResourceRequest& request,
+      const ResourceResponse& redirect_response,
+      Resource::Type,
+      const FetchInitiatorInfo& = FetchInitiatorInfo()) override {
+    will_send_request_ = request;
+  }
   bool AllowImage(bool images_enabled, const KURL&) const override {
     return true;
   }
@@ -144,6 +158,7 @@ class MockFetchContext : public FetchContext {
   std::unique_ptr<WebURLLoaderFactory> url_loader_factory_;
   bool complete_;
   long long transfer_size_;
+  WTF::Optional<ResourceRequest> will_send_request_;
 };
 
 }  // namespace blink