Bug 1019840 - Use cached intrinsic size in nsImageFrame::ComputeSize unless the image loader has a size. r=tn

dom/base/nsIImageLoadingContent.idl

@@ -28,16 +28,11 @@ interface nsIFrame;
  * become current only when the image is loaded.  It is the responsibility of
  * observers to check which request they are getting notifications for.
  *
- * Observers added in mid-load will not get any notifications they
- * missed.  We should NOT freeze this interface without considering
- * this issue.  (It could be that the image status on imgIRequest is
- * sufficient, when combined with the imageBlockingStatus information.)
- *
  * Please make sure to update the MozImageLoadingContent WebIDL
  * interface to mirror this interface when changing it.
  */
 
-[scriptable, builtinclass, uuid(5794d12b-3195-4526-a814-a2181f6c71fe)]
+[scriptable, builtinclass, uuid(770f7d84-c917-42d7-bf8d-d1b70649e733)]
 interface nsIImageLoadingContent : imgINotificationObserver
 {
   /**
@@ -100,6 +95,11 @@ interface nsIImageLoadingContent : imgINotificationObserver
    */
   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.

dom/base/nsImageLoadingContent.cpp

@@ -493,6 +493,12 @@ nsImageLoadingContent::GetRequest(int32_t aRequestType,
   return result.ErrorCode();
 }
 
+NS_IMETHODIMP_(bool)
+nsImageLoadingContent::CurrentRequestHasSize()
+{
+  return HaveSize(mCurrentRequest);
+}
+
 NS_IMETHODIMP_(void)
 nsImageLoadingContent::FrameCreated(nsIFrame* aFrame)
 {

layout/generic/nsImageFrame.cpp

@@ -743,10 +743,18 @@ nsImageFrame::ComputeSize(nsRenderingContext *aRenderingContext,
   NS_ASSERTION(imageLoader, "No content node??");
   mozilla::IntrinsicSize intrinsicSize(mIntrinsicSize);
 
+  // XXX(seth): We may sometimes find ourselves in the situation where we have
+  // mImage, but imageLoader's current request does not have a size yet.
+  // This can happen when we load an image speculatively from cache, it fails
+  // to validate, and the new image load hasn't fired SIZE_AVAILABLE yet. In
+  // this situation we should always use mIntrinsicSize, because
+  // GetNaturalWidth/Height will return 0, so we check CurrentRequestHasSize()
+  // below. See bug 1019840. We will fix this in bug 1141395.
+
   // Content may override our default dimensions. This is termed as overriding
   // the intrinsic size by the spec, but all other consumers of mIntrinsic*
   // values are being used to refer to the real/true size of the image data.
-  if (imageLoader && mImage &&
+  if (imageLoader && imageLoader->CurrentRequestHasSize() && mImage &&
       intrinsicSize.width.GetUnit() == eStyleUnit_Coord &&
       intrinsicSize.height.GetUnit() == eStyleUnit_Coord) {
     uint32_t width;