Bug 1084136 (Part 6) - Don't reset any imgStatusTracker state when discarding. r=tn

--HG--
extra : rebase_source : 48b0bb6827f6b8121f662bab4dcfb823fa8fe870

image/src/imgDecoderObserver.h

@@ -109,13 +109,6 @@ public:
    */
   virtual void OnStopRequest(bool aIsLastPart, nsresult aStatus) = 0;
 
-  /**
-   * Called when the decoded image data is discarded. This means that the frames
-   * no longer exist in decoded form, and any attempt to access or draw the
-   * image will initiate a new series of progressive decode notifications.
-   */
-  virtual void OnDiscard() = 0;
-
   /**
    * Called when we are asked to Draw an image that is not locked.
    */

image/src/imgStatusTracker.cpp

@@ -107,14 +107,6 @@ public:
     tracker->RecordStopRequest(aLastPart, aStatus);
   }
 
-  virtual void OnDiscard() MOZ_OVERRIDE
-  {
-    LOG_SCOPE(GetImgLog(), "imgStatusTrackerObserver::OnDiscard");
-    nsRefPtr<imgStatusTracker> tracker = mTracker.get();
-    if (!tracker) { return; }
-    tracker->RecordDiscard();
-  }
-
   virtual void OnUnlockedDraw() MOZ_OVERRIDE
   {
     LOG_SCOPE(GetImgLog(), "imgStatusTrackerObserver::OnUnlockedDraw");
@@ -715,22 +707,6 @@ imgStatusTracker::SendStopDecode(imgRequestProxy* aProxy,
     aProxy->OnStopDecode();
 }
 
-void
-imgStatusTracker::RecordDiscard()
-{
-  NS_ABORT_IF_FALSE(mImage,
-                    "RecordDiscard called before we have an Image");
-  // Clear the state bits we no longer deserve.
-  uint32_t stateBitsToClear = FLAG_DECODE_STOPPED;
-  mState &= ~stateBitsToClear;
-
-  // Clear the status bits we no longer deserve.
-  uint32_t statusBitsToClear = imgIRequest::STATUS_DECODE_STARTED |
-                               imgIRequest::STATUS_FRAME_COMPLETE |
-                               imgIRequest::STATUS_DECODE_COMPLETE;
-  mImageStatus &= ~statusBitsToClear;
-}
-
 void
 imgStatusTracker::SendDiscard(imgRequestProxy* aProxy)
 {
@@ -929,7 +905,6 @@ void
 imgStatusTracker::OnDiscard()
 {
   MOZ_ASSERT(NS_IsMainThread());
-  RecordDiscard();
 
   /* notify the kids */
   ProxyArray::ForwardIterator iter(mConsumers);

image/src/imgStatusTracker.h

@@ -210,7 +210,6 @@ public:
   void SendStopFrame(imgRequestProxy* aProxy);
   void RecordStopDecode(nsresult statusg);
   void SendStopDecode(imgRequestProxy* aProxy, nsresult aStatus);
-  void RecordDiscard();
   void SendDiscard(imgRequestProxy* aProxy);
   void RecordUnlockedDraw();
   void SendUnlockedDraw(imgRequestProxy* aProxy);

image/test/browser/browser_bug666317.js

@@ -10,11 +10,37 @@ let prefBranch = Cc["@mozilla.org/preferences-service;1"]
                    .getService(Ci.nsIPrefService)
                    .getBranch('image.mem.');
 
-function isImgDecoded() {
+function ImageDiscardObserver(result) {
+  this.discard = function onDiscard(request)
+  {
+    result.wasDiscarded = true;
+    this.synchronous = false;
+  }
+
+  this.synchronous = true;
+}
+
+function currentRequest() {
   let img = gBrowser.getBrowserForTab(newTab).contentWindow
             .document.getElementById('testImg');
   img.QueryInterface(Ci.nsIImageLoadingContent);
-  let request = img.getRequest(Ci.nsIImageLoadingContent.CURRENT_REQUEST);
+  return img.getRequest(Ci.nsIImageLoadingContent.CURRENT_REQUEST);
+}
+
+function attachDiscardObserver(result) {
+  // Create the discard observer.
+  let observer = new ImageDiscardObserver(result);
+  let scriptedObserver = Cc["@mozilla.org/image/tools;1"]
+                           .getService(Ci.imgITools)
+                           .createScriptedObserver(observer);
+
+  // Clone the current imgIRequest with our new observer.
+  let request = currentRequest();
+  return request.clone(scriptedObserver);
+}
+
+function isImgDecoded() {
+  let request = currentRequest();
   return request.imageStatus & Ci.imgIRequest.STATUS_FRAME_COMPLETE ? true : false;
 }
 
@@ -43,6 +69,10 @@ function test() {
 }
 
 function step2() {
+  // Attach a discard listener and create a place to hold the result.
+  var result = { wasDiscarded: false };
+  var clonedRequest = attachDiscardObserver(result);
+
   // Check that the image is decoded.
   forceDecodeImg();
   ok(isImgDecoded(), 'Image should initially be decoded.');
@@ -53,10 +83,11 @@ function step2() {
   var os = Cc["@mozilla.org/observer-service;1"]
              .getService(Ci.nsIObserverService);
   os.notifyObservers(null, 'memory-pressure', 'heap-minimize');
-  ok(!isImgDecoded(), 'Image should be discarded.');
+  ok(result.wasDiscarded, 'Image should be discarded.');
 
   // And we're done.
   gBrowser.removeTab(newTab);
   prefBranch.setBoolPref('discardable', oldDiscardingPref);
+  clonedRequest.cancelAndForgetObserver(0);
   finish();
 }