MemoryCache: make sure that Resources are evicted only when they can be deleted

Source/core/fetch/Resource.h

Index: Source/core/fetch/Resource.h
diff --git a/Source/core/fetch/Resource.h b/Source/core/fetch/Resource.h
index 6714f2989bb4f3dead0dfc46e41c3abd4f820878..dd982b6eb58b64d5c5cebd17e769228ba88d2a02 100644
--- a/Source/core/fetch/Resource.h
+++ b/Source/core/fetch/Resource.h
@@ -197,8 +197,8 @@ public:
     // Returns cached metadata of the given type associated with this resource.
     CachedMetadata* cachedMetadata(unsigned dataTypeID) const;
 
-    bool canDelete() const { return !hasClients() && !m_loader && !m_preloadCount && !m_handleCount && !m_protectorCount && !m_resourceToRevalidate && !m_proxyResource; }
-    bool hasOneHandle() const { return m_handleCount == 1; }
+    bool canDelete();

[Philippe, 2014/03/26 16:04:07]

Nit: did you drop the 'const' here intentionally? We should also be able to add
it back on line 201 (right below) and line 345.

I see that MemoryCache::contains() is not only not const but also takes a
mutable pointer to Resource which is why you had to drop the const here I guess.
I think this is a mistake, please consider making it have the following
signature instead: "bool MemoryCache::contains(const Resource*) const".

[Philippe, 2014/03/26 17:08:33]

Just sent this CL to Nate so that you can add the 'const' back here:
https://chromiumcodereview.appspot.com/213193002/ :)

[clamy, 2014/03/27 10:47:16]

Thanks! I will make them const again.

+    bool hasOneHandleApartFromCache();
 
     // List of acceptable MIME types separated by ",".
     // A MIME type may contain a wildcard, e.g. "text/*".
@@ -342,6 +342,8 @@ private:
 
     bool unlock();
 
+    bool hasRightHandleCountApartFromCache(unsigned targetCount);
+
     void failBeforeStarting();
 
     String m_fragmentIdentifierForRequest;