--- a/image/decoders/nsBMPDecoder.cpp
+++ b/image/decoders/nsBMPDecoder.cpp
@@ -10,17 +10,16 @@
 #include <stdlib.h>
 
 #include "ImageLogging.h"
 #include "EndianMacros.h"
 #include "nsBMPDecoder.h"
 
 #include "nsIInputStream.h"
 #include "RasterImage.h"
-#include "imgIContainerObserver.h"
 
 namespace mozilla {
 namespace image {
 
 #ifdef PR_LOGGING
 static PRLogModuleInfo *
 GetBMPLog()
 {

--- a/image/decoders/nsGIFDecoder2.cpp
+++ b/image/decoders/nsGIFDecoder2.cpp
@@ -37,17 +37,16 @@ organizations who wish to receive copies
 or revised. This service is offered free of charge; please provide us with your
 mailing address.
 */
 
 #include <stddef.h>
 
 #include "nsGIFDecoder2.h"
 #include "nsIInputStream.h"
-#include "imgIContainerObserver.h"
 #include "RasterImage.h"
 
 #include "gfxColor.h"
 #include "gfxPlatform.h"
 #include "qcms.h"
 
 namespace mozilla {
 namespace image {

--- a/image/decoders/nsICODecoder.cpp
+++ b/image/decoders/nsICODecoder.cpp
@@ -9,17 +9,16 @@
 #include <stdlib.h>
 
 #include "EndianMacros.h"
 #include "nsICODecoder.h"
 
 #include "nsIInputStream.h"
 #include "nsIComponentManager.h"
 #include "RasterImage.h"
-#include "imgIContainerObserver.h"
 
 #include "nsIProperties.h"
 #include "nsISupportsPrimitives.h"
 
 namespace mozilla {
 namespace image {
 
 #define ICONCOUNTOFFSET 4

--- a/image/decoders/nsIconDecoder.cpp
+++ b/image/decoders/nsIconDecoder.cpp
@@ -2,17 +2,16 @@
  *
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "nsIconDecoder.h"
 #include "nsIInputStream.h"
 #include "RasterImage.h"
-#include "imgIContainerObserver.h"
 #include "nspr.h"
 #include "nsRect.h"
 
 #include "nsError.h"
 
 namespace mozilla {
 namespace image {
 

--- a/image/decoders/nsJPEGDecoder.cpp
+++ b/image/decoders/nsJPEGDecoder.cpp
@@ -2,18 +2,16 @@
  *
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "ImageLogging.h"
 #include "nsJPEGDecoder.h"
 
-#include "imgIContainerObserver.h"
-
 #include "nsIInputStream.h"
 
 #include "nspr.h"
 #include "nsCRT.h"
 #include "gfxColor.h"
 
 #include "jerror.h"
 

--- a/image/decoders/nsPNGDecoder.cpp
+++ b/image/decoders/nsPNGDecoder.cpp
@@ -8,17 +8,16 @@
 #include "nsPNGDecoder.h"
 
 #include "nsMemory.h"
 #include "nsRect.h"
 
 #include "nsIInputStream.h"
 
 #include "RasterImage.h"
-#include "imgIContainerObserver.h"
 
 #include "gfxColor.h"
 #include "nsColor.h"
 
 #include "nspr.h"
 #include "png.h"
 
 #include "gfxPlatform.h"

--- a/image/public/Makefile.in
+++ b/image/public/Makefile.in
@@ -14,17 +14,16 @@ MODULE		= imglib2
 GRE_MODULE	= 1
 
 EXPORTS		= ImageLogging.h
 
 XPIDLSRCS	= \
 		imgICache.idl             \
 		imgIContainer.idl         \
 		imgIContainerDebug.idl    \
-		imgIContainerObserver.idl \
 		imgIDecoderObserver.idl   \
 		imgIEncoder.idl           \
 		imgILoader.idl            \
 		imgINotificationObserver.idl \
 		imgIOnloadBlocker.idl     \
 		imgIRequest.idl           \
 		imgIScriptedNotificationObserver.idl \
 		imgITools.idl             \

deleted file mode 100644
--- a/image/public/imgIContainerObserver.idl
+++ /dev/null
@@ -1,26 +0,0 @@
-/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
- *
- * This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-#include "nsISupports.idl"
-
-%{C++
-#include "nsRect.h"
-%}
-
-interface imgIRequest;
-[ptr] native nsIntRect(nsIntRect);
-
-/**
- * imgIContainerObserver interface
- *
- * @author Stuart Parmenter <pavlov@netscape.com>
- * @version 0.1
- */
-[scriptable, uuid(f4aaf410-e88f-4036-b91c-610c9c11d825)]
-interface imgIContainerObserver : nsISupports
-{
-  [noscript] void frameChanged([const] in nsIntRect aDirtyRect);
-};

--- a/image/public/imgIDecoderObserver.idl
+++ b/image/public/imgIDecoderObserver.idl
@@ -1,23 +1,22 @@
 /** -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
  *
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "imgIContainerObserver.idl"
-
-interface imgIRequest;
-interface imgIContainer;
+#include "nsISupports.idl"
 
 %{C++
 #include "nsRect.h"
 %}
 
+[ptr] native nsIntRect(nsIntRect);
+
 /**
  * imgIDecoderObserver interface
  *
  * This interface is used both for observing imgIDecoder objects and for
  * observing imgIRequest objects.  In the former case, aRequest is
  * always null.
  *
  * We make the distinction here between "load" and "decode" notifications. Load
@@ -38,18 +37,18 @@ interface imgIContainer;
  * all, some, or none of the notifications may fire before the call returns.
  *
  * This interface will be cleaned up in bug 505385.
  *
  * @author Stuart Parmenter <pavlov@netscape.com>
  * @version 0.1
  * @see imagelib2
  */
-[scriptable, uuid(0089cf0c-210c-4b44-9ab0-8099b32bcf64)]
-interface imgIDecoderObserver : imgIContainerObserver
+[scriptable, uuid(eb9f4145-247e-44f5-961d-50da7d08fba7)]
+interface imgIDecoderObserver : nsISupports
 {
   /**
    * Load notification.
    *
    * called at the same time that nsIRequestObserver::onStartRequest would be
    * (used only for observers of imgIRequest objects, which are nsIRequests,
    * not imgIDecoder objects)
    */
@@ -76,16 +75,18 @@ interface imgIDecoderObserver : imgICont
 
   /**
    * Decode notification.
    *
    * called when there is more to paint.
    */
   [noscript] void onDataAvailable([const] in nsIntRect aRect);
 
+  [noscript] void frameChanged([const] in nsIntRect aDirtyRect);
+
   /**
    * Decode notification.
    *
    * called when a frame is finished decoding.
    */
   void onStopFrame();
 
   /**

--- a/image/src/RasterImage.cpp
+++ b/image/src/RasterImage.cpp
@@ -1,17 +1,17 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "base/histogram.h"
 #include "ImageLogging.h"
 #include "nsComponentManagerUtils.h"
-#include "imgIContainerObserver.h"
+#include "imgIDecoderObserver.h"
 #include "nsError.h"
 #include "Decoder.h"
 #include "imgIDecoderObserver.h"
 #include "RasterImage.h"
 #include "nsIInterfaceRequestor.h"
 #include "nsIInterfaceRequestorUtils.h"
 #include "nsAutoPtr.h"
 #include "nsStringStream.h"
@@ -633,17 +633,17 @@ RasterImage::RequestRefresh(const mozill
     // then we need to break out of this loop & wait for the frame(s)
     // to finish downloading
     if (!frameAdvanced && (currentFrameEndTime == oldFrameEndTime)) {
       break;
     }
   }
 
   if (frameAdvanced) {
-    nsCOMPtr<imgIContainerObserver> observer(do_QueryReferent(mObserver));
+    nsCOMPtr<imgIDecoderObserver> observer(do_QueryReferent(mObserver));
 
     if (!observer) {
       NS_ERROR("Refreshing image after its imgRequest is gone");
       StopAnimation();
       return;
     }
 
     // Notify listeners that our frame has actually changed, but do this only
@@ -1655,17 +1655,17 @@ RasterImage::ResetAnimation()
   mAnim->lastCompositedFrameIndex = -1;
   mAnim->currentAnimationFrameIndex = 0;
   UpdateImageContainer();
 
   // Note - We probably want to kick off a redecode somewhere around here when
   // we fix bug 500402.
 
   // Update display if we were animating before
-  nsCOMPtr<imgIContainerObserver> observer(do_QueryReferent(mObserver));
+  nsCOMPtr<imgIDecoderObserver> observer(do_QueryReferent(mObserver));
   if (mAnimating && observer)
     observer->FrameChanged(&(mAnim->firstFrameRefreshArea));
 
   if (ShouldAnimate()) {
     StartAnimation();
     // The animation may not have been running before, if mAnimationFinished
     // was false (before we changed it to true in this function). So, mark the
     // animation as running.
@@ -2907,17 +2907,17 @@ void
 RasterImage::ScalingDone(ScaleRequest* request, ScaleStatus status)
 {
   MOZ_ASSERT(status == SCALE_DONE || status == SCALE_INVALID);
   MOZ_ASSERT(request);
 
   if (status == SCALE_DONE) {
     MOZ_ASSERT(request->done);
 
-    nsCOMPtr<imgIContainerObserver> observer(do_QueryReferent(mObserver));
+    nsCOMPtr<imgIDecoderObserver> observer(do_QueryReferent(mObserver));
     if (observer) {
       imgFrame *scaledFrame = request->dstFrame.get();
       scaledFrame->ImageUpdated(scaledFrame->GetRect());
       observer->FrameChanged(&request->srcRect);
     }
 
     mScaleResult.status = SCALE_DONE;
     mScaleResult.frame = request->dstFrame;

--- a/image/src/RasterImage.h
+++ b/image/src/RasterImage.h
@@ -35,17 +35,16 @@
 #include "mozilla/StaticPtr.h"
 #include "mozilla/WeakPtr.h"
 #include "gfx2DGlue.h"
 #ifdef DEBUG
   #include "imgIContainerDebug.h"
 #endif
 
 class imgIDecoder;
-class imgIContainerObserver;
 class nsIInputStream;
 
 #define NS_RASTERIMAGE_CID \
 { /* 376ff2c1-9bf6-418a-b143-3340c00112f7 */         \
      0x376ff2c1,                                     \
      0x9bf6,                                         \
      0x418a,                                         \
     {0xb1, 0x43, 0x33, 0x40, 0xc0, 0x01, 0x12, 0xf7} \

--- a/image/src/VectorImage.cpp
+++ b/image/src/VectorImage.cpp
@@ -746,21 +746,17 @@ VectorImage::OnDataAvailable(nsIRequest*
 // Invalidation helper method
 
 void
 VectorImage::InvalidateObserver()
 {
   if (!mObserver)
     return;
 
-  nsCOMPtr<imgIContainerObserver> containerObs(do_QueryReferent(mObserver));
-  if (containerObs) {
-    containerObs->FrameChanged(&nsIntRect::GetMaxSizedIntRect());
-  }
-
-  nsCOMPtr<imgIDecoderObserver> decoderObs(do_QueryReferent(mObserver));
-  if (decoderObs) {
-    decoderObs->OnStopFrame();
+  nsCOMPtr<imgIDecoderObserver> obs(do_QueryReferent(mObserver));
+  if (obs) {
+    obs->FrameChanged(&nsIntRect::GetMaxSizedIntRect());
+    obs->OnStopFrame();
   }
 }
 
 } // namespace image
 } // namespace mozilla

--- a/image/src/imgStatusTracker.cpp
+++ b/image/src/imgStatusTracker.cpp
@@ -4,16 +4,17 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "imgStatusTracker.h"
 
 #include "imgRequest.h"
 #include "imgIContainer.h"
 #include "imgRequestProxy.h"
+#include "imgIDecoderObserver.h"
 #include "Image.h"
 #include "ImageLogging.h"
 #include "RasterImage.h"
 #include "nsIObserverService.h"
 
 #include "mozilla/Util.h"
 #include "mozilla/Assertions.h"
 #include "mozilla/Services.h"
@@ -21,55 +22,34 @@
 using namespace mozilla::image;
 
 class imgStatusTrackerObserver : public imgIDecoderObserver,
                                  public nsSupportsWeakReference
 {
 public:
   NS_DECL_ISUPPORTS
   NS_DECL_IMGIDECODEROBSERVER
-  NS_DECL_IMGICONTAINEROBSERVER
 
   imgStatusTrackerObserver(imgStatusTracker* aTracker)
   : mTracker(aTracker) {}
 
   virtual ~imgStatusTrackerObserver() {}
 
   void SetTracker(imgStatusTracker* aTracker) {
     mTracker = aTracker;
   }
 
 private:
   imgStatusTracker* mTracker;
 };
 
-NS_IMPL_ISUPPORTS3(imgStatusTrackerObserver,
+NS_IMPL_ISUPPORTS2(imgStatusTrackerObserver,
                    imgIDecoderObserver,
-                   imgIContainerObserver,
                    nsISupportsWeakReference)
 
-/** imgIContainerObserver methods **/
-
-/* [noscript] void frameChanged (in nsIntRect dirtyRect); */
-NS_IMETHODIMP imgStatusTrackerObserver::FrameChanged(const nsIntRect *dirtyRect)
-{
-  LOG_SCOPE(GetImgLog(), "imgStatusTrackerObserver::FrameChanged");
-  NS_ABORT_IF_FALSE(mTracker->GetImage(),
-                    "FrameChanged callback before we've created our image");
-
-  mTracker->RecordFrameChanged(dirtyRect);
-
-  nsTObserverArray<imgRequestProxy*>::ForwardIterator iter(mTracker->mConsumers);
-  while (iter.HasMore()) {
-    mTracker->SendFrameChanged(iter.GetNext(), dirtyRect);
-  }
-
-  return NS_OK;
-}
-
 /** imgIDecoderObserver methods **/
 
 NS_IMETHODIMP imgStatusTrackerObserver::OnStartDecode()
 {
   LOG_SCOPE(GetImgLog(), "imgStatusTrackerObserver::OnStartDecode");
   NS_ABORT_IF_FALSE(mTracker->GetImage(),
                     "OnStartDecode callback before we've created our image");
 
@@ -132,16 +112,33 @@ NS_IMETHODIMP imgStatusTrackerObserver::
   nsTObserverArray<imgRequestProxy*>::ForwardIterator iter(mTracker->mConsumers);
   while (iter.HasMore()) {
     mTracker->SendDataAvailable(iter.GetNext(), rect);
   }
 
   return NS_OK;
 }
 
+/* [noscript] void frameChanged (in nsIntRect dirtyRect); */
+NS_IMETHODIMP imgStatusTrackerObserver::FrameChanged(const nsIntRect *dirtyRect)
+{
+  LOG_SCOPE(GetImgLog(), "imgStatusTrackerObserver::FrameChanged");
+  NS_ABORT_IF_FALSE(mTracker->GetImage(),
+                    "FrameChanged callback before we've created our image");
+
+  mTracker->RecordFrameChanged(dirtyRect);
+
+  nsTObserverArray<imgRequestProxy*>::ForwardIterator iter(mTracker->mConsumers);
+  while (iter.HasMore()) {
+    mTracker->SendFrameChanged(iter.GetNext(), dirtyRect);
+  }
+
+  return NS_OK;
+}
+
 /* void onStopFrame (); */
 NS_IMETHODIMP imgStatusTrackerObserver::OnStopFrame()
 {
   LOG_SCOPE(GetImgLog(), "imgStatusTrackerObserver::OnStopFrame");
   NS_ABORT_IF_FALSE(mTracker->GetImage(),
                     "OnStopFrame callback before we've created our image");
 
   mTracker->RecordStopFrame();
@@ -634,17 +631,16 @@ imgStatusTracker::RecordImageIsAnimated(
 
 void
 imgStatusTracker::SendDiscard(imgRequestProxy* aProxy)
 {
   if (!aProxy->NotificationsDeferred())
     aProxy->OnDiscard();
 }
 
-/* non-virtual imgIContainerObserver methods */
 void
 imgStatusTracker::RecordFrameChanged(const nsIntRect* aDirtyRect)
 {
   NS_ABORT_IF_FALSE(mImage,
                     "RecordFrameChanged called before we have an Image");
   // no bookkeeping necessary here - this is only for in-frame updates, which we
   // don't fire while we're recording
 }

--- a/image/src/imgStatusTracker.h
+++ b/image/src/imgStatusTracker.h
@@ -127,29 +127,27 @@ public:
   // StartFrame, DataAvailable, StopFrame, StopDecode.
   void RecordDecoded();
 
   /* non-virtual imgIDecoderObserver methods */
   void RecordStartContainer(imgIContainer* aContainer);
   void SendStartContainer(imgRequestProxy* aProxy);
   void RecordDataAvailable();
   void SendDataAvailable(imgRequestProxy* aProxy, const nsIntRect* aRect);
+  void RecordFrameChanged(const nsIntRect* aDirtyRect);
+  void SendFrameChanged(imgRequestProxy* aProxy, const nsIntRect* aDirtyRect);
   void RecordStopFrame();
   void SendStopFrame(imgRequestProxy* aProxy);
   void RecordStopDecode(nsresult statusg);
   void SendStopDecode(imgRequestProxy* aProxy, nsresult aStatus);
   void RecordDiscard();
   void SendDiscard(imgRequestProxy* aProxy);
   void RecordImageIsAnimated();
   void SendImageIsAnimated(imgRequestProxy *aProxy);
 
-  /* non-virtual imgIContainerObserver methods */
-  void RecordFrameChanged(const nsIntRect* aDirtyRect);
-  void SendFrameChanged(imgRequestProxy* aProxy, const nsIntRect* aDirtyRect);
-
   /* non-virtual sort-of-nsIRequestObserver methods */
   void RecordStartRequest();
   void SendStartRequest(imgRequestProxy* aProxy);
   void RecordStopRequest(bool aLastPart, nsresult aStatus);
   void SendStopRequest(imgRequestProxy* aProxy, bool aLastPart, nsresult aStatus);
 
   void OnStartRequest();
   void OnDataAvailable();

--- a/image/src/imgTools.cpp
+++ b/image/src/imgTools.cpp
@@ -8,17 +8,16 @@
 #include "nsCOMPtr.h"
 #include "nsString.h"
 #include "nsError.h"
 #include "imgLoader.h"
 #include "imgICache.h"
 #include "imgIContainer.h"
 #include "imgIEncoder.h"
 #include "imgIDecoderObserver.h"
-#include "imgIContainerObserver.h"
 #include "gfxContext.h"
 #include "nsStringStream.h"
 #include "nsComponentManagerUtils.h"
 #include "nsWeakReference.h"
 #include "nsIInterfaceRequestorUtils.h"
 #include "nsStreamUtils.h"
 #include "nsNetUtil.h"
 #include "nsContentUtils.h"

--- a/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp
+++ b/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp
@@ -47,17 +47,16 @@
 #include "nsNetUtil.h"
 #include "nsBoxLayoutState.h"
 #include "nsTreeContentView.h"
 #include "nsTreeUtils.h"
 #include "nsChildIterator.h"
 #include "nsITheme.h"
 #include "imgIRequest.h"
 #include "imgIContainer.h"
-#include "imgIContainerObserver.h"
 #include "imgILoader.h"
 #include "nsINodeInfo.h"
 #include "nsContentUtils.h"
 #include "nsLayoutUtils.h"
 #include "nsIScrollableFrame.h"
 #include "nsEventDispatcher.h"
 #include "nsDisplayList.h"
 #include "nsTreeBoxObject.h"