Preload scan external CSS for @import

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 26a3cb189f0ec67210f4ab9d4805a1f6aeb214de..6a92ff5372c586675130660aaf5a38b60b259e2b 100644
--- a/third_party/WebKit/Source/core/fetch/CSSStyleSheetResource.cpp
+++ b/third_party/WebKit/Source/core/fetch/CSSStyleSheetResource.cpp
@@ -51,6 +51,7 @@ CSSStyleSheetResource* CSSStyleSheetResource::createForTest(const ResourceReques
 
 CSSStyleSheetResource::CSSStyleSheetResource(const ResourceRequest& resourceRequest, const ResourceLoaderOptions& options, const String& charset)
     : StyleSheetResource(resourceRequest, CSSStyleSheet, options, "text/css", charset)
+    , m_didNotifyFirstData(false)
 {
 }
 
@@ -80,6 +81,8 @@ void CSSStyleSheetResource::didAddClient(ResourceClient* c)
     // because setCSSStyleSheet() may cause scripts to be executed, which could destroy 'c' if it is an instance of HTMLLinkElement.
     // see the comment of HTMLLinkElement::setCSSStyleSheet.
     Resource::didAddClient(c);
+    if (m_didNotifyFirstData)
+        static_cast<StyleSheetResourceClient*>(c)->didAppendFirstData(this);

[hiroshige, 2016/07/26 09:57:10]

|*c| must not be destructed during didAppendFirstData() (to prevent similar
issues to crbug.com/612132 (restricted)).

oilpan-reviews, is |*c| kept alive, or should we add
    Persistent<StyleSheetResourceClient> protect = c
?
- |c| points to StyleSheetResourceClient, an on-heap subclass of ResourceClient.
- |c| appears on the C++ stack as an argument of didAddClient() here, but as
ResourceClient*, not as StyleSheetResourceClient*.
- ResourceClient is not on-heap.

[haraken, 2016/07/26 10:01:06]

You won't need Persistent<StyleSheetResourceClient>. Oilpan will keep alive |*c|
on the stack since Oilpan keeps alive all on-stack pointers that exist in the
heap region.

 
     if (!isLoading())

[hiroshige, 2016/07/26 09:57:10]

|c| might be removed as client in didAppendFirstData() in general.
So please check that |c| is still an client, i.e.
    if (hasClient(c) && !isLoading())

[Charlie Harrison, 2016/07/26 16:31:52]

Done.

         static_cast<StyleSheetResourceClient*>(c)->setCSSStyleSheet(m_resourceRequest.url(), m_response.url(), encoding(), this);
@@ -99,6 +102,17 @@ const String CSSStyleSheetResource::sheetText(MIMETypeCheck mimeTypeCheck) const
     return decodedText();
 }
 
+void CSSStyleSheetResource::appendData(const char* data, size_t length)
+{
+    Resource::appendData(data, length);
+    if (m_didNotifyFirstData)
+        return;
+    ResourceClientWalker<StyleSheetResourceClient> w(clients());
+    while (StyleSheetResourceClient* c = w.next())
+        c->didAppendFirstData(this);
+    m_didNotifyFirstData = true;
+}
+
 void CSSStyleSheetResource::checkNotify()
 {
     // Decode the data to find out the encoding and keep the sheet text around during checkNotify()