Raise the loading priority of in-viewport images.

Source/core/fetch/ResourceLoadPriorityOptimizer.h

Index: Source/core/fetch/ResourceLoadPriorityOptimizer.h
diff --git a/Source/core/dom/DocumentLifecycle.h b/Source/core/fetch/ResourceLoadPriorityOptimizer.h
similarity index 67%
copy from Source/core/dom/DocumentLifecycle.h
copy to Source/core/fetch/ResourceLoadPriorityOptimizer.h
index c3f919635e833a43521a5a7e401602671935c4f6..e2da705c185f804a23a66f412d921f5abbce4ad6 100644
--- a/Source/core/dom/DocumentLifecycle.h
+++ b/Source/core/fetch/ResourceLoadPriorityOptimizer.h
@@ -28,34 +28,36 @@
  * 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,
-    };
-
-    DocumentLifecycle();
-    ~DocumentLifecycle();
+    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.

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