Raise the loading priority of in-viewport images.

Source/core/fetch/ResourceLoadPriorityOptimizer.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 10 matching lines @@
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef DocumentLifecycle_h
-#define DocumentLifecycle_h
+#ifndef ResourceLoadPriorityOptimizer_h
+#define ResourceLoadPriorityOptimizer_h
 
-#include "wtf/Noncopyable.h"
+#include "core/fetch/ImageResource.h"
+#include "core/fetch/ResourcePtr.h"
+
+#include <map>
 
 namespace WebCore {
 
-class DocumentLifecycle {
-    WTF_MAKE_NONCOPYABLE(DocumentLifecycle);
+class ResourceLoadPriorityOptimizer {
 public:
-    enum State {
-        Uninitialized,
-        Inactive,
-        Active,
-        Stopping,
-        Stopped,
-        Disposed,
+    ResourceLoadPriorityOptimizer();
+    ~ResourceLoadPriorityOptimizer();
+    void notifyImageResourceVisibility(ImageResource*, bool);

[eseidel, 2013/11/25 23:59:30]

Bools make awful args.  We try to use Enums when possible.  Even if those enums
only ahve 2 values.  They tend to be much easier to read.

[shatch, 2013/11/26 01:35:18]

Done.

+
+private:
+    void updateImageResourcesWithLoadPriority();
+
+    struct ResourceAndVisibility {
+        ResourceAndVisibility(ImageResource*, bool);
+        ResourceAndVisibility();
+        ResourceAndVisibility(const ResourceAndVisibility&);
+        ~ResourceAndVisibility();
+        ResourcePtr<ImageResource> imageResource;
+        bool visible;
     };
 
-    DocumentLifecycle();
-    ~DocumentLifecycle();
-
-    State state() const { return m_state; }
-
-    void advanceTo(State);
-
-private:
-    State m_state;
+    typedef std::map<unsigned long, ResourceAndVisibility> ImageResourceMap;

[eseidel, 2013/11/25 23:59:30]

I don't recall.  Is "unsigned long" actually different from "unsigned"?

Curious why not HashMap like other blink code?  We've talked about moving more
twoards std:: types, but right now I believe WTF types are preferred when
available.

[shatch, 2013/11/26 01:35:18]

I'm not sure if they're different? A quick search revealed:
http://stackoverflow.com/questions/2099830/unsigned-keyword-in-c which claims
when "unsigned" is used by itself, a data type of "int" is assumed. Searching on
int vs long revealed that ints could theoretically be smaller than longs
(http://stackoverflow.com/questions/7456902/long-vs-int-c-c-whats-the-point).
Honestly though, I just copied the return value of Resource::identifier(). Do
you want me to change this to an unsigned?

I remember seeing a thread on that in blink-dev back in July, wasn't sure what
the current status was. I mostly just used std::map because I'm familiar with
it, but I don't have a strong opinion on the subject. Changed it to a HashMap.

+    ImageResourceMap m_imageResources;
 };
 
 }
 
 #endif