Cache-aware Resource loading

third_party/WebKit/Source/core/fetch/ResourceLoader.cpp

Index: third_party/WebKit/Source/core/fetch/ResourceLoader.cpp
diff --git a/third_party/WebKit/Source/core/fetch/ResourceLoader.cpp b/third_party/WebKit/Source/core/fetch/ResourceLoader.cpp
index c9e4d3c4ad80eeea93dee39b13d3bad95bea8aac..189ab4a06002ccf8d4b11b6dca655e4c0fa52598 100644
--- a/third_party/WebKit/Source/core/fetch/ResourceLoader.cpp
+++ b/third_party/WebKit/Source/core/fetch/ResourceLoader.cpp
@@ -54,7 +54,9 @@ ResourceLoader* ResourceLoader::create(ResourceFetcher* fetcher,
 }
 
 ResourceLoader::ResourceLoader(ResourceFetcher* fetcher, Resource* resource)
-    : m_fetcher(fetcher), m_resource(resource) {
+    : m_fetcher(fetcher),
+      m_resource(resource),
+      m_isCacheAwareLoadingActivated(false) {
   DCHECK(m_resource);
   DCHECK(m_fetcher);
   m_resource->setLoader(this);
@@ -69,7 +71,7 @@ DEFINE_TRACE(ResourceLoader) {
   visitor->trace(m_resource);
 }
 
-void ResourceLoader::start(const ResourceRequest& request,
+void ResourceLoader::start(const ResourceRequest& originalRequest,
                            WebTaskRunner* loadingTaskRunner,
                            bool defersLoading) {
   DCHECK(!m_loader);
@@ -79,6 +81,15 @@ void ResourceLoader::start(const ResourceRequest& request,
     return;
   }
 
+  // This is only for overriding cache policy if cache-aware loading is
+  // activated.
+  ResourceRequest request(originalRequest);
+
+  if (m_isCacheAwareLoadingActivated) {
+    // TODO(shaochuan): Use new flag
+    request.setCachePolicy(WebCachePolicy::ReturnCacheDataDontLoad);
+  }
+
   m_loader = wrapUnique(Platform::current()->createURLLoader());
   DCHECK(m_loader);
   m_loader->setDefersLoading(defersLoading);
@@ -137,6 +148,13 @@ bool ResourceLoader::willFollowRedirect(
   DCHECK(!passedNewRequest.isNull());
   DCHECK(!passedRedirectResponse.isNull());
 
+  if (m_isCacheAwareLoadingActivated) {
+    // Fail as cache miss if cached response is a redirect.
+    didFail(
+        ResourceError::cacheMissError(m_resource->lastResourceRequest().url()));
+    return false;
+  }
+
   ResourceRequest& newRequest(passedNewRequest.toMutableResourceRequest());
   const ResourceResponse& redirectResponse(
       passedRedirectResponse.toResourceResponse());
@@ -269,4 +287,22 @@ void ResourceLoader::requestSynchronously(const ResourceRequest& request) {
   didFinishLoading(0, monotonicallyIncreasingTime(), encodedDataLength);
 }
 
+bool ResourceLoader::willActivateCacheAwareLoading(
+    const ResourceRequest& request) {
+  // Don't activate on Resource revalidation.
+  if (m_resource->isCacheValidator())
+    return false;
+  // Don't activate if cache policy is explicitly set.
+  if (request.getCachePolicy() != WebCachePolicy::UseProtocolCachePolicy)
+    return false;
+
+  m_isCacheAwareLoadingActivated = true;
+  return true;
+}
+
+void ResourceLoader::deactivateCacheAwareLoading() {
+  DCHECK(m_isCacheAwareLoadingActivated);
+  m_isCacheAwareLoadingActivated = false;
+}
+
 }  // namespace blink