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 9fbabee79622c331ba92247f7abdc00eb8968b9a..eb40978860e3fca808ffaa2067353813a1b43c93 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);
@@ -190,9 +192,11 @@ void ImageLoader::updateFromElement()
         m_hasPendingErrorEvent = true;
         errorEventSender().dispatchEventSoon(this);
     }
-    
+
     CachedImage* oldImage = m_image.get();
     if (newImage != oldImage) {
+        sourceImageChanged();
+
         if (m_hasPendingBeforeLoadEvent) {
             beforeLoadEventSender().cancelEvent(this);
             m_hasPendingBeforeLoadEvent = false;
@@ -423,6 +427,26 @@ void ImageLoader::dispatchPendingErrorEvent()
     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();
@@ -444,6 +468,15 @@ 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();