Allow eviction of ImageBitmaps that are created from ImageElements.

Source/core/loader/ImageLoader.cpp

Index: Source/core/loader/ImageLoader.cpp
diff --git a/Source/core/loader/ImageLoader.cpp b/Source/core/loader/ImageLoader.cpp
index 612a04bd3dd65a11b07a9979f04f237670db862a..ec0ed7b3c1ebf3788593bcca990c6b48560099a8 100644
--- a/Source/core/loader/ImageLoader.cpp
+++ b/Source/core/loader/ImageLoader.cpp
@@ -75,6 +75,7 @@ ImageLoader::ImageLoader(Element* element)
     , m_imageComplete(true)
     , m_loadManually(false)
     , m_elementIsProtected(false)
+    , m_highPriorityClientCount(0)
 {
 }
 
@@ -115,6 +116,7 @@ void ImageLoader::setImageWithoutConsideringPendingLoadEvent(CachedImage* newIma
     ASSERT(m_failedLoadURL.isEmpty());
     CachedImage* oldImage = m_image.get();
     if (newImage != oldImage) {
+        sourceImageChanged();
         m_image = newImage;
         if (m_hasPendingBeforeLoadEvent) {
             beforeLoadEventSender().cancelEvent(this);
@@ -193,6 +195,8 @@ void ImageLoader::updateFromElement()
 
     CachedImage* oldImage = m_image.get();
     if (newImage != oldImage) {
+        sourceImageChanged();
+
         if (m_hasPendingBeforeLoadEvent) {
             beforeLoadEventSender().cancelEvent(this);
             m_hasPendingBeforeLoadEvent = false;
@@ -426,6 +430,25 @@ void ImageLoader::dispatchPendingErrorEvent()
     updatedHasPendingEvent();
 }
 
+void ImageLoader::addClient(ImageLoaderClient* client)
+{
+    if (client->requestsHighLiveResourceCachePriority()) {
+        if (m_image && !m_highPriorityClientCount++)
+            m_image->setCacheLiveResourcePriority(Resource::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(Resource::CacheLiveResourcePriorityLow);
+    }
+    m_clients.remove(client);
+}
+
 void ImageLoader::dispatchPendingBeforeLoadEvents()
 {
     beforeLoadEventSender().dispatchPendingEvents();
@@ -447,6 +470,15 @@ void ImageLoader::elementDidMoveToNewDocument()
     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();