CSSStyleSheetResource should cache decoded text instead of raw bytes

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

Index: third_party/WebKit/Source/core/fetch/CSSStyleSheetResource.cpp
diff --git a/third_party/WebKit/Source/core/fetch/CSSStyleSheetResource.cpp b/third_party/WebKit/Source/core/fetch/CSSStyleSheetResource.cpp
index 72ee750b8984a5cdbd8a84e040f535449bb2458b..856685402a9fefd2238ded939aeca866f9121d96 100644
--- a/third_party/WebKit/Source/core/fetch/CSSStyleSheetResource.cpp
+++ b/third_party/WebKit/Source/core/fetch/CSSStyleSheetResource.cpp
@@ -43,8 +43,12 @@ CSSStyleSheetResource* CSSStyleSheetResource::fetch(FetchRequest& request,
             WebURLRequest::FrameTypeNone);
   request.mutableResourceRequest().setRequestContext(
       WebURLRequest::RequestContextStyle);
-  return toCSSStyleSheetResource(
+  CSSStyleSheetResource* resource = toCSSStyleSheetResource(
       fetcher->requestResource(request, CSSStyleSheetResourceFactory()));
+  // TODO(kouhei): Dedupe this logic w/ ScriptResource::fetch
+  if (resource && !request.integrityMetadata().isEmpty())
+    resource->setIntegrityMetadata(request.integrityMetadata());
+  return resource;
 }
 
 CSSStyleSheetResource* CSSStyleSheetResource::createForTest(
@@ -99,14 +103,21 @@ void CSSStyleSheetResource::didAddClient(ResourceClient* c) {
 
 const String CSSStyleSheetResource::sheetText(
     MIMETypeCheck mimeTypeCheck) const {
-  if (!data() || data()->isEmpty() || !canUseSheet(mimeTypeCheck))
+  if (!canUseSheet(mimeTypeCheck))
     return String();
 
-  if (!m_decodedSheetText.isNull())
+  // Use cached decoded sheet text when available
+  if (!m_decodedSheetText.isNull()) {
+    // We should have the decoded sheet text cached when the resource is fully
+    // loaded.
+    DCHECK_EQ(getStatus(), Resource::Cached);
+
     return m_decodedSheetText;
+  }
+
+  if (!data() || data()->isEmpty())
+    return String();
 
-  // Don't cache the decoded text, regenerating is cheap and it can use quite a
-  // bit of memory
   return decodedText();
 }
 
@@ -121,10 +132,10 @@ void CSSStyleSheetResource::appendData(const char* data, size_t length) {
 }
 
 void CSSStyleSheetResource::checkNotify() {
-  // Decode the data to find out the encoding and keep the sheet text around
-  // during checkNotify()
-  if (data())
+  // Decode the data to find out the encoding and cache the decoded sheet text.
+  if (data()) {
     m_decodedSheetText = decodedText();
+  }
 
   ResourceClientWalker<StyleSheetResourceClient> w(clients());
   while (StyleSheetResourceClient* c = w.next()) {
@@ -132,9 +143,13 @@ void CSSStyleSheetResource::checkNotify() {
     c->setCSSStyleSheet(resourceRequest().url(), response().url(), encoding(),
                         this);
   }
-  // Clear the decoded text as it is unlikely to be needed immediately again and
-  // is cheap to regenerate.
-  m_decodedSheetText = String();
+
+  // Clear raw bytes as now we have the full decoded sheet text.
+  // We wait for all LinkStyle::setCSSStyleSheet to run (at least once)
+  // as SubresourceIntegrity checks require raw bytes.
+  // Note that LinkStyle::setCSSStyleSheet can be called from didAddClient too,
+  // but is safe as we should have a cached ResourceIntegrityDisposition.
+  clearData();
 }
 
 void CSSStyleSheetResource::destroyDecodedDataIfPossible() {
@@ -145,6 +160,11 @@ void CSSStyleSheetResource::destroyDecodedDataIfPossible() {
   setDecodedSize(0);
 }
 
+void CSSStyleSheetResource::destroyDecodedDataForFailedRevalidation() {
+  m_decodedSheetText = String();
+  destroyDecodedDataIfPossible();
+}
+
 bool CSSStyleSheetResource::canUseSheet(MIMETypeCheck mimeTypeCheck) const {
   if (errorOccurred())
     return false;