Handle multiple incomplete lazy decoded frames

Handle multiple incomplete lazy decoded frames in
DeferredImageDecoder::PrepareLazyDecodedFrames().

This allows blink::ImageDecoder::DecodeFrameCount() to return the true
frame count even when not all frames' encoded data are available.

Change blink::AVIFImageDecoder::DecodeFrameCount() to return the true
frame count.

Change blink::AVIFImageDecoder::FrameIsReceivedAtIndex() to actually
check if the frame's encoded data has been received.

Bug: 1148577
Bug: 1136922
Change-Id: I2423472b406b130fb460cbfe65b5b3890c106344
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2538696
Commit-Queue: Wan-Teh Chang <wtc@google.com>
Reviewed-by: Khushal <khushalsagar@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Chris Blume <cblume@chromium.org>
Cr-Commit-Position: refs/heads/master@{#828390}

third_party/blink/renderer/platform/graphics/deferred_image_decoder.cc

@@ -440,15 +440,12 @@ void DeferredImageDecoder::PrepareLazyDecodedFrames() {
     frame_data_[i].duration_ = metadata_decoder_->FrameDurationAtIndex(i);
     frame_data_[i].orientation_ = metadata_decoder_->Orientation();
     frame_data_[i].density_corrected_size_ = metadata_decoder_->DensityCorrectedSize();
-    frame_data_[i].is_received_ = metadata_decoder_->FrameIsReceivedAtIndex(i);
   }
 
-  // The last lazy decoded frame created from previous call might be
-  // incomplete so update its state.
-  if (previous_size) {
-    const size_t last_frame = previous_size - 1;
-    frame_data_[last_frame].is_received_ =
-        metadata_decoder_->FrameIsReceivedAtIndex(last_frame);
+  // Update the is_received_ state of incomplete frames.
+  while (received_frame_count_ < frame_data_.size() &&
+         metadata_decoder_->FrameIsReceivedAtIndex(received_frame_count_)) {
+    frame_data_[received_frame_count_++].is_received_ = true;
   }
 
   can_yuv_decode_ =

third_party/blink/renderer/platform/graphics/deferred_image_decoder.h

@@ -131,6 +131,9 @@ class PLATFORM_EXPORT DeferredImageDecoder final {
 
   // Caches frame state information.
   Vector<DeferredFrameData> frame_data_;
+  // The number of received/complete frames in |frame_data_|. Note: This is also
+  // the index of the first unreceived/incomplete frame in |frame_data_|.
+  size_t received_frame_count_ = 0;
   scoped_refptr<ImageFrameGenerator> frame_generator_;
 
   DISALLOW_COPY_AND_ASSIGN(DeferredImageDecoder);

third_party/blink/renderer/platform/image-decoders/avif/avif_image_decoder.cc

@@ -464,11 +464,9 @@ bool AVIFImageDecoder::FrameIsReceivedAtIndex(size_t index) const {
     return false;
   if (decoded_frame_count_ == 1)
     return ImageDecoder::FrameIsReceivedAtIndex(index);
-  // frame_buffer_cache_.size() is equal to the return value of
-  // DecodeFrameCount(). Since DecodeFrameCount() returns the number of frames
-  // whose encoded data have been received, we can return true if |index| is
-  // valid for frame_buffer_cache_. See crbug.com/1148577.
-  return index < frame_buffer_cache_.size();
+  return index < frame_buffer_cache_.size() &&
+         (IsAllDataReceived() ||
+          avifDecoderNthImageReady(decoder_.get(), index) == AVIF_RESULT_OK);
 }
 
 base::TimeDelta AVIFImageDecoder::FrameDurationAtIndex(size_t index) const {
@@ -530,19 +528,8 @@ void AVIFImageDecoder::DecodeSize() {
 size_t AVIFImageDecoder::DecodeFrameCount() {
   if (!Failed())
     ParseMetadata();
-  if (!IsDecodedSizeAvailable())
-    return frame_buffer_cache_.size();
-  if (decoded_frame_count_ == 1 || IsAllDataReceived())
-    return decoded_frame_count_;
-  // For a multi-frame image, Chrome expects DecodeFrameCount() to return the
-  // number of frames whose encoded data have been received.
-  size_t index;
-  for (index = frame_buffer_cache_.size(); index < decoded_frame_count_;
-       ++index) {
-    if (avifDecoderNthImageReady(decoder_.get(), index) != AVIF_RESULT_OK)
-      break;
-  }
-  return index;
+  return IsDecodedSizeAvailable() ? decoded_frame_count_
+                                  : frame_buffer_cache_.size();
 }
 
 void AVIFImageDecoder::InitializeNewFrame(size_t index) {