Turn off isLinkPreload() when used

third_party/WebKit/Source/core/fetch/Resource.h

Index: third_party/WebKit/Source/core/fetch/Resource.h
diff --git a/third_party/WebKit/Source/core/fetch/Resource.h b/third_party/WebKit/Source/core/fetch/Resource.h
index 70428fc06439fa2947416d13f9a3cb08b2b4ef80..903d178c6c628478dcb57b9c6ab9576dbc8d5fe8 100644
--- a/third_party/WebKit/Source/core/fetch/Resource.h
+++ b/third_party/WebKit/Source/core/fetch/Resource.h
@@ -214,6 +214,9 @@ public:
     DataBufferingPolicy getDataBufferingPolicy() const { return m_options.dataBufferingPolicy; }
     void setDataBufferingPolicy(DataBufferingPolicy);
 
+    // The isPreloaded() flag is using a counter in order to make sure that even when
+    // multiple ResourceFetchers are preloading the resource, it will remain marked as
+    // preloaded until *all* of them have used it.
     bool isUnusedPreload() const { return isPreloaded() && getPreloadResult() == PreloadNotReferenced; }
     bool isPreloaded() const { return m_preloadCount; }
     void increasePreloadCount() { ++m_preloadCount; }
@@ -253,6 +256,8 @@ public:
 
     static const char* resourceTypeToString(Type, const FetchInitiatorInfo&);
 
+    void testOnlyWillAddClientOrObserver(PreloadReferencePolicy policy) { willAddClientOrObserver(policy); }

[Yoav Weiss, 2016/09/13 09:33:18]

Adding this test only method, since adding an actual observer (even a Mock one)
resulted in weird crashes around the m_observers HashCountedSet, which I suspect
is the result of it not being thread safe.

[Nate Chapin, 2016/09/13 22:34:17]

...this is all single threaded, isn't it? This explanation sounds suspect to me.
Are you sure the observer was getting both added and removed?

[Charlie Harrison, 2016/09/16 12:18:47]

I think a "ForTesting" suffix is more common and I think (?) it gets checked by
a presubmit that the method is only used for tests.

[Charlie Harrison, 2016/09/16 12:31:38]

Apologies this was a very out of date draft comment :)

+
 protected:
     Resource(const ResourceRequest&, Type, const ResourceLoaderOptions&);