Adds a feature to MHTML serialization that omits subframes and subresources marked no-store.

third_party/WebKit/Source/core/frame/FrameSerializer.h

Index: third_party/WebKit/Source/core/frame/FrameSerializer.h
diff --git a/third_party/WebKit/Source/core/frame/FrameSerializer.h b/third_party/WebKit/Source/core/frame/FrameSerializer.h
index 9aaf155303aa327a2b38ecb37bc3f76ff5d6ceef..d6c1c8ba8b4f60deb1843c3cc1df87ac2d355612 100644
--- a/third_party/WebKit/Source/core/frame/FrameSerializer.h
+++ b/third_party/WebKit/Source/core/frame/FrameSerializer.h
@@ -85,9 +85,15 @@ public:
             return false;
         }
 
-        // Tells whether to skip serialization of a subresource with a given URI.
-        // Used to deduplicate resources across multiple frames.
-        virtual bool shouldSkipResource(const KURL&)
+        // Tells whether to skip serialization of a subresource or CSSStyleSheet
+        // with a given URI. Used to deduplicate resources across multiple frames.
+        virtual bool shouldSkipResourceWithURL(const KURL&)

[Łukasz Anforowicz, 2016/05/19 17:00:13]

Nice name change.  Long time ago this was also used to check if a subframe
should be skipped, but right now (as the name change correctly highlights) this
is only used for subresources.

[dewittj, 2016/05/19 18:18:36]

Acknowledged.

+        {
+            return false;
+        }
+
+        // Tells whether to skip serialization of a subresource.
+        virtual bool shouldSkipResource(Resource*)
         {
             return false;
         }