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diff --git a/dom/base/nsIImageLoadingContent.idl b/dom/base/nsIImageLoadingContent.idl
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+++ b/dom/base/nsIImageLoadingContent.idl
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+/* -*- 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 "imgINotificationObserver.idl"
+
+%{C++
+#include "mozilla/Maybe.h"
+#include "Visibility.h"
+%}
+
+interface imgIRequest;
+interface nsIChannel;
+interface nsIStreamListener;
+interface nsIURI;
+interface nsIDocument;
+interface nsIFrame;
+
+[ref] native MaybeOnNonvisible(const mozilla::Maybe<mozilla::OnNonvisible>);
+native Visibility(mozilla::Visibility);
+
+/**
+ * This interface represents a content node that loads images.  The interface
+ * exists to allow getting information on the images that the content node
+ * loads and to allow registration of observers for the image loads.
+ *
+ * Implementors of this interface should handle all the mechanics of actually
+ * loading an image -- getting the URI, checking with content policies and
+ * the security manager to see whether loading the URI is allowed, performing
+ * the load, firing any DOM events as needed.
+ *
+ * An implementation of this interface may support the concepts of a
+ * "current" image and a "pending" image.  If it does, a request to change
+ * the currently loaded image will start a "pending" request which will
+ * become current only when the image is loaded.  It is the responsibility of
+ * observers to check which request they are getting notifications for.
+ *
+ * Please make sure to update the MozImageLoadingContent WebIDL
+ * interface to mirror this interface when changing it.
+ */
+
+[scriptable, builtinclass, uuid(0357123d-9224-4d12-a47e-868c32689777)]
+interface nsIImageLoadingContent : imgINotificationObserver
+{
+  /**
+   * Request types.  Image loading content nodes attempt to do atomic
+   * image changes when the image url is changed.  This means that
+   * when the url changes the new image load will start, but the old
+   * image will remain the "current" request until the new image is
+   * fully loaded.  At that point, the old "current" request will be
+   * discarded and the "pending" request will become "current".
+   */
+  const long UNKNOWN_REQUEST = -1;
+  const long CURRENT_REQUEST = 0;
+  const long PENDING_REQUEST = 1;
+
+  /**
+   * loadingEnabled is used to enable and disable loading in
+   * situations where loading images is unwanted.  Note that enabling
+   * loading will *not* automatically trigger an image load.
+   */
+  attribute boolean loadingEnabled;
+
+  /**
+   * Returns the image blocking status (@see nsIContentPolicy).  This
+   * will always be an nsIContentPolicy REJECT_* status for cases when
+   * the image was blocked.  This status always refers to the
+   * CURRENT_REQUEST load.
+   */
+  readonly attribute short imageBlockingStatus;
+
+  /**
+   * Used to register an image decoder observer.  Typically, this will
+   * be a proxy for a frame that wants to paint the image.
+   * Notifications from ongoing image loads will be passed to all
+   * registered observers.  Notifications for all request types,
+   * current and pending, will be passed through.
+   *
+   * @param aObserver the observer to register
+   *
+   * @throws NS_ERROR_OUT_OF_MEMORY
+   */
+  void addObserver(in imgINotificationObserver aObserver);
+
+  /**
+   * Used to unregister an image decoder observer.
+   *
+   * @param aObserver the observer to unregister
+   */
+  void removeObserver(in imgINotificationObserver aObserver);
+  
+  /**
+   * Accessor to get the image requests
+   *
+   * @param aRequestType a value saying which request is wanted
+   *
+   * @return the imgIRequest object (may be null, even when no error
+   * is thrown)
+   *
+   * @throws NS_ERROR_UNEXPECTED if the request type requested is not
+   * known
+   */
+  imgIRequest getRequest(in long aRequestType);
+
+  /**
+   * @return true if the current request's size is available.
+   */
+  [noscript, notxpcom] boolean currentRequestHasSize();
+
+  /**
+   * Used to notify the image loading content node that a frame has been
+   * created.
+   */
+  [notxpcom] void frameCreated(in nsIFrame aFrame);
+
+  /**
+   * Used to notify the image loading content node that a frame has been
+   * destroyed.
+   */
+  [notxpcom] void frameDestroyed(in nsIFrame aFrame);
+
+  /**
+   * Used to find out what type of request one is dealing with (eg
+   * which request got passed through to the imgINotificationObserver
+   * interface of an observer)
+   *
+   * @param aRequest the request whose type we want to know
+   *
+   * @return an enum value saying what type this request is
+   *
+   * @throws NS_ERROR_UNEXPECTED if aRequest is not known
+   */
+  long getRequestType(in imgIRequest aRequest);
+
+  /**
+   * Gets the URI of the current request, if available.
+   * Otherwise, returns the last URI that this content tried to load, or
+   * null if there haven't been any such attempts.
+   */
+  readonly attribute nsIURI currentURI;
+
+  /**
+   * loadImageWithChannel allows data from an existing channel to be
+   * used as the image data for this content node.
+   *
+   * @param aChannel the channel that will deliver the data
+   *
+   * @return a stream listener to pump the image data into
+   *
+   * @see imgILoader::loadImageWithChannel
+   *
+   * @throws NS_ERROR_NULL_POINTER if aChannel is null
+   */
+  nsIStreamListener loadImageWithChannel(in nsIChannel aChannel);
+
+  /**
+   * forceReload forces reloading of the image pointed to by currentURI
+   *
+   * @param aNotify [optional] request should notify, defaults to true
+   * @throws NS_ERROR_NOT_AVAILABLE if there is no current URI to reload
+   */
+  [optional_argc] void forceReload([optional] in boolean aNotify /* = true */);
+
+  /**
+   * Enables/disables image state forcing. When |aForce| is PR_TRUE, we force
+   * nsImageLoadingContent::ImageState() to return |aState|. Call again with |aForce|
+   * as PR_FALSE to revert ImageState() to its original behaviour.
+   */
+  void forceImageState(in boolean aForce, in unsigned long long aState);
+
+  /**
+   * The intrinsic size and width of this content. May differ from actual image
+   * size due to things like responsive image density.
+   */
+  readonly attribute unsigned long    naturalWidth;
+  readonly attribute unsigned long    naturalHeight;
+
+  /**
+   * Called by layout to announce when the frame associated with this content
+   * has changed its visibility state.
+   *
+   * @param aNewVisibility    The new visibility state.
+   * @param aNonvisibleAction A requested action if the frame has become
+   *                          nonvisible. If Nothing(), no action is
+   *                          requested. If DISCARD_IMAGES is specified, the
+   *                          frame is requested to ask any images it's
+   *                          associated with to discard their surfaces if
+   *                          possible.
+   */
+  [noscript, notxpcom] void onVisibilityChange(in Visibility aNewVisibility,
+                                               in MaybeOnNonvisible aNonvisibleAction);
+};