Enable `as` based priorities for <link rel=preload>

Source/core/loader/LinkLoaderTest.cpp

Index: Source/core/loader/LinkLoaderTest.cpp
diff --git a/Source/core/loader/LinkLoaderTest.cpp b/Source/core/loader/LinkLoaderTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..c9a8215753a134974b644f8efb2a3d1fdb90c4fe
--- /dev/null
+++ b/Source/core/loader/LinkLoaderTest.cpp
@@ -0,0 +1,78 @@
+// Copyright 2015 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 "config.h"
+#include "core/loader/LinkLoader.h"
+
+#include "core/fetch/ResourceFetcher.h"
+#include "core/html/LinkRelAttribute.h"
+#include "core/loader/LinkLoaderClient.h"
+#include "core/testing/DummyPageHolder.h"
+#include "platform/network/ResourceLoadPriority.h"
+
+#include <base/macros.h>
+#include <gtest/gtest.h>
+
+namespace blink {
+
+class MockLinkLoaderClient : public LinkLoaderClient {
+public:
+    MockLinkLoaderClient(bool shouldLoad)
+        : m_shouldLoad(shouldLoad)
+    {
+    }
+
+    virtual bool shouldLoadLink() override
+    {
+        return m_shouldLoad;
+    }
+
+    virtual void linkLoaded() override { }
+    virtual void linkLoadingErrored() override { }
+    virtual void didStartLinkPrerender() override { }
+    virtual void didStopLinkPrerender() override { }
+    virtual void didSendLoadForLinkPrerender() override { }
+    virtual void didSendDOMContentLoadedForLinkPrerender() override { }
+
+private:
+    bool m_shouldLoad;
+};
+
+TEST(LinkLoaderTest, Preload)
+{
+    struct TestCase {
+        const char* href;
+        const char* as;
+        const ResourceLoadPriority priority;
+        const bool shouldLoad;
+    } cases[] = {
+        {"data://example.com/cat.jpg", "image", ResourceLoadPriorityVeryLow, true},
+        {"data://example.com/cat.jpg", "script", ResourceLoadPriorityMedium, true},
+        {"data://example.com/cat.jpg", "stylesheet", ResourceLoadPriorityHigh, true},
+        {"data://example.com/cat.jpg", "blabla", ResourceLoadPriorityUnresolved, true},
+        {"data://example.com/cat.jpg", "image", ResourceLoadPriorityUnresolved, false},
+    };
+
+    // Test the cases with a single header
+    for (const auto& testCase : cases) {
+        OwnPtr<DummyPageHolder> dummyPageHolder = DummyPageHolder::create(IntSize(500, 500));
+        MockLinkLoaderClient loaderClient(testCase.shouldLoad);
+        LinkLoader loader(&loaderClient);
+        KURL hrefURL = KURL(KURL(), testCase.href);
+        loader.loadLink(LinkRelAttribute("preload"),
+            AtomicString(),
+            String(),
+            testCase.as,
+            hrefURL,
+            dummyPageHolder->document());
+        if (testCase.priority == ResourceLoadPriorityUnresolved) {
+            ASSERT(!loader.resource());
+        } else {
+            ASSERT(loader.resource());
+            ASSERT_EQ(testCase.priority, loader.resource()->resourceRequest().priority());
+        }
+    }
+}
+
+} // namespace blink