Actually handle the Vary header in blink, rather than punting on sight.

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

Index: third_party/WebKit/Source/platform/loader/fetch/ResourceTest.cpp
diff --git a/third_party/WebKit/Source/platform/loader/fetch/ResourceTest.cpp b/third_party/WebKit/Source/platform/loader/fetch/ResourceTest.cpp
index a421b170e8a9f71744d5ea51eeaa7f598af58684..a887e4298ba11eb5811b786eb27b3001f5ffccb4 100644
--- a/third_party/WebKit/Source/platform/loader/fetch/ResourceTest.cpp
+++ b/third_party/WebKit/Source/platform/loader/fetch/ResourceTest.cpp
@@ -90,4 +90,61 @@ TEST(ResourceTest, RevalidateWithFragment) {
   resource->responseReceived(revalidatingResponse, nullptr);
 }
 
+TEST(ResourceTest, Vary) {
+  ScopedTestingPlatformSupport<MockPlatform> mock;
+  KURL url(ParsedURLString, "http://127.0.0.1:8000/foo.html");
+  ResourceResponse response;
+  response.setURL(url);
+  response.setHTTPStatusCode(200);
+
+  Resource* resource = RawResource::create(url, Resource::Raw);
+  resource->responseReceived(response, nullptr);
+  resource->finish();
+
+  ResourceRequest newRequest(url);
+  EXPECT_FALSE(resource->mustReloadDueToVaryHeader(newRequest));
+
+  response.setHTTPHeaderField(HTTPNames::Vary, "*");
+  resource->setResponse(response);
+  EXPECT_TRUE(resource->mustReloadDueToVaryHeader(newRequest));
+
+  // Irrelevant header
+  response.setHTTPHeaderField(HTTPNames::Vary, "definitelynotarealheader");
+  resource->setResponse(response);
+  EXPECT_FALSE(resource->mustReloadDueToVaryHeader(newRequest));
+
+  // Header present on new but not old
+  newRequest.setHTTPHeaderField(HTTPNames::User_Agent, "something");
+  response.setHTTPHeaderField(HTTPNames::Vary, HTTPNames::User_Agent);
+  resource->setResponse(response);
+  EXPECT_TRUE(resource->mustReloadDueToVaryHeader(newRequest));
+  newRequest.clearHTTPHeaderField(HTTPNames::User_Agent);
+
+  ResourceRequest oldRequest(url);
+  oldRequest.setHTTPHeaderField(HTTPNames::User_Agent, "something");
+  oldRequest.setHTTPHeaderField(HTTPNames::Referer, "http://foo.com");
+  resource = RawResource::create(oldRequest, Resource::Raw);
+  resource->responseReceived(response, nullptr);
+  resource->finish();
+
+  // Header present on old but not new
+  newRequest.clearHTTPHeaderField(HTTPNames::User_Agent);
+  response.setHTTPHeaderField(HTTPNames::Vary, HTTPNames::User_Agent);
+  resource->setResponse(response);
+  EXPECT_TRUE(resource->mustReloadDueToVaryHeader(newRequest));
+
+  // Header present on both
+  newRequest.setHTTPHeaderField(HTTPNames::User_Agent, "something");
+  EXPECT_FALSE(resource->mustReloadDueToVaryHeader(newRequest));
+
+  // One matching, one mismatching
+  response.setHTTPHeaderField(HTTPNames::Vary, "User-Agent, Referer");
+  resource->setResponse(response);
+  EXPECT_TRUE(resource->mustReloadDueToVaryHeader(newRequest));
+
+  // Two matching
+  newRequest.setHTTPHeaderField(HTTPNames::Referer, "http://foo.com");
+  EXPECT_FALSE(resource->mustReloadDueToVaryHeader(newRequest));
+}
+
 }  // namespace blink