Allow eviction of ImageBitmaps that are created from ImageElements.

Source/core/loader/ImageLoader.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 57 matching lines @@
 ImageLoader::ImageLoader(Element* element)
     : m_element(element)
     , m_image(0)
     , m_derefElementTimer(this, &ImageLoader::timerFired)
     , m_hasPendingBeforeLoadEvent(false)
     , m_hasPendingLoadEvent(false)
     , m_hasPendingErrorEvent(false)
     , m_imageComplete(true)
     , m_loadManually(false)
     , m_elementIsProtected(false)
+    , m_highPriorityClientCount(0)
 {
 }
 
 ImageLoader::~ImageLoader()
 {
     if (m_image)
         m_image->removeClient(this);
 
     ASSERT(m_hasPendingBeforeLoadEvent || !beforeLoadEventSender().hasPendingEvents(this));
     if (m_hasPendingBeforeLoadEvent)
@@ skipping 20 matching lines @@
     // Only consider updating the protection ref-count of the Element immediately before returning
     // from this function as doing so might result in the destruction of this ImageLoader.
     updatedHasPendingEvent();
 }
 
 void ImageLoader::setImageWithoutConsideringPendingLoadEvent(CachedImage* newImage)
 {
     ASSERT(m_failedLoadURL.isEmpty());
     CachedImage* oldImage = m_image.get();
     if (newImage != oldImage) {
+        sourceImageChanged();
         m_image = newImage;
         if (m_hasPendingBeforeLoadEvent) {
             beforeLoadEventSender().cancelEvent(this);
             m_hasPendingBeforeLoadEvent = false;
         }
         if (m_hasPendingLoadEvent) {
             loadEventSender().cancelEvent(this);
             m_hasPendingLoadEvent = false;
         }
         if (m_hasPendingErrorEvent) {
@@ skipping 55 matching lines @@
             m_failedLoadURL = attr;
             m_hasPendingErrorEvent = true;
             errorEventSender().dispatchEventSoon(this);
         } else
             clearFailedLoadURL();
     } else if (!attr.isNull()) {
         // Fire an error event if the url is empty.
         m_hasPendingErrorEvent = true;
         errorEventSender().dispatchEventSoon(this);
     }
-    
+
     CachedImage* oldImage = m_image.get();
     if (newImage != oldImage) {
+        sourceImageChanged();
+
         if (m_hasPendingBeforeLoadEvent) {
             beforeLoadEventSender().cancelEvent(this);
             m_hasPendingBeforeLoadEvent = false;
         }
         if (m_hasPendingLoadEvent) {
             loadEventSender().cancelEvent(this);
             m_hasPendingLoadEvent = false;
         }
 
         // Cancel error events that belong to the previous load, which is now cancelled by changing the src attribute.
@@ skipping 210 matching lines @@
         return;
     m_hasPendingErrorEvent = false;
     if (element()->document()->attached())
         element()->dispatchEvent(Event::create(eventNames().errorEvent, false, false));
 
     // Only consider updating the protection ref-count of the Element immediately before returning
     // from this function as doing so might result in the destruction of this ImageLoader.
     updatedHasPendingEvent();
 }
 
+void ImageLoader::addClient(ImageLoaderClient* client)
+{
+    if (client->requestsHighLiveResourceCachePriority()) {
+        m_highPriorityClientCount++;
+        if (m_image)

[Justin Novosad, 2013/07/29 17:47:58]

Better to only call setCacheLiveResourcePriority if necessary. Suggestion: if
(m_image && !m_highPriorityClientCount++)

+            m_image->setCacheLiveResourcePriority(CachedResource::CacheLiveResourcePriorityHigh);
+    }
+    m_clients.add(client);
+}
+void ImageLoader::removeClient(ImageLoaderClient* client)
+{
+    if (client->requestsHighLiveResourceCachePriority()) {
+        ASSERT(m_highPriorityClientCount);
+        m_highPriorityClientCount--;
+        if (m_image && !m_highPriorityClientCount)
+            m_image->setCacheLiveResourcePriority(CachedResource::CacheLiveResourcePriorityLow);
+    }
+    m_clients.remove(client);
+}
+
 void ImageLoader::dispatchPendingBeforeLoadEvents()
 {
     beforeLoadEventSender().dispatchPendingEvents();
 }
 
 void ImageLoader::dispatchPendingLoadEvents()
 {
     loadEventSender().dispatchPendingEvents();
 }
 
 void ImageLoader::dispatchPendingErrorEvents()
 {
     errorEventSender().dispatchPendingEvents();
 }
 
 void ImageLoader::elementDidMoveToNewDocument()
 {
     clearFailedLoadURL();
     setImage(0);
 }
 
+void ImageLoader::sourceImageChanged()
+{
+    HashSet<ImageLoaderClient*>::iterator end = m_clients.end();
+    for (HashSet<ImageLoaderClient*>::iterator it = m_clients.begin(); it != end; ++it) {
+        ImageLoaderClient* handle = *it;
+        handle->notifyImageSourceChanged();
+    }
+}
+
 inline void ImageLoader::clearFailedLoadURL()
 {
     m_failedLoadURL = AtomicString();
 }
 
 }