diff --git a/api/video/video_frame.cc b/api/video/video_frame.cc
index 4075bf7..5cd909c 100644
--- a/api/video/video_frame.cc
+++ b/api/video/video_frame.cc
@@ -156,6 +156,7 @@
 
 void VideoFrame::set_video_frame_buffer(
     rtc::scoped_refptr<VideoFrameBuffer> buffer) {
+  RTC_CHECK(buffer.get());
   video_frame_buffer_ = buffer;
 }
 
diff --git a/video/BUILD.gn b/video/BUILD.gn
index cb02610..cfe20c4 100644
--- a/video/BUILD.gn
+++ b/video/BUILD.gn
@@ -175,8 +175,6 @@
     "encoder_overshoot_detector.h",
     "overuse_frame_detector.cc",
     "overuse_frame_detector.h",
-    "partial_frame_assembler.cc",
-    "partial_frame_assembler.h",
     "video_stream_encoder.cc",
     "video_stream_encoder.h",
   ]
@@ -483,7 +481,6 @@
       "end_to_end_tests/stats_tests.cc",
       "end_to_end_tests/transport_feedback_tests.cc",
       "overuse_frame_detector_unittest.cc",
-      "partial_frame_assembler_unittest.cc",
       "picture_id_tests.cc",
       "quality_scaling_tests.cc",
       "quality_threshold_unittest.cc",
diff --git a/video/partial_frame_assembler.cc b/video/partial_frame_assembler.cc
deleted file mode 100644
index e7d1c12..0000000
--- a/video/partial_frame_assembler.cc
+++ /dev/null
@@ -1,96 +0,0 @@
-/*
- *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#include "video/partial_frame_assembler.h"
-
-#include "rtc_base/checks.h"
-#include "rtc_base/logging.h"
-#include "rtc_base/ref_counted_object.h"
-
-namespace webrtc {
-
-PartialFrameAssembler::PartialFrameAssembler() = default;
-PartialFrameAssembler::~PartialFrameAssembler() = default;
-
-bool PartialFrameAssembler::ApplyPartialUpdate(
-    const rtc::scoped_refptr<VideoFrameBuffer>& input_buffer,
-    VideoFrame* uncompressed_frame,
-    const VideoFrame::PartialFrameDescription* partial_desc) {
-  const int changed_rect_width = input_buffer ? input_buffer->width() : 0;
-  const int changed_rect_height = input_buffer ? input_buffer->height() : 0;
-  if (partial_desc == nullptr) {
-    // Full update. Copy whole picture to the cached buffer. May need to
-    // resize or create the cache buffer.
-    if (!cached_frame_buffer_ ||
-        cached_frame_buffer_->height() < input_buffer->height() ||
-        cached_frame_buffer_->width() < input_buffer->width()) {
-      cached_frame_buffer_ =
-          I420Buffer::Create(input_buffer->width(), input_buffer->height());
-    }
-    cached_frame_buffer_->PasteFrom(*input_buffer->ToI420().get(), 0, 0);
-  } else {
-    // Have to apply partial input picture to the cached buffer.
-    // Check all possible error situations.
-    if (!cached_frame_buffer_) {
-      RTC_LOG(LS_ERROR) << "Partial picture received but no cached full picture"
-                           "present.";
-      return false;
-    }
-    if (partial_desc->offset_x % 2 != 0 || partial_desc->offset_y % 2 != 0) {
-      RTC_LOG(LS_ERROR) << "Partial picture required to be at even offset."
-                           " Actual: ("
-                        << partial_desc->offset_x << ", "
-                        << partial_desc->offset_y << ").";
-      cached_frame_buffer_ = nullptr;
-      return false;
-    }
-    if ((changed_rect_width % 2 != 0 &&
-         changed_rect_width + partial_desc->offset_x <
-             cached_frame_buffer_->width()) ||
-        (changed_rect_height % 2 != 0 &&
-         changed_rect_height + partial_desc->offset_y <
-             cached_frame_buffer_->height())) {
-      RTC_LOG(LS_ERROR) << "Partial picture required to have even dimensions."
-                           " Actual: "
-                        << input_buffer->width() << "x"
-                        << input_buffer->height() << ".";
-      cached_frame_buffer_ = nullptr;
-      return false;
-    }
-    if (partial_desc->offset_x < 0 ||
-        partial_desc->offset_x + changed_rect_width >
-            cached_frame_buffer_->width() ||
-        partial_desc->offset_y < 0 ||
-        partial_desc->offset_y + changed_rect_height >
-            cached_frame_buffer_->height()) {
-      RTC_LOG(LS_ERROR) << "Partial picture is outside of bounds.";
-      cached_frame_buffer_ = nullptr;
-      return false;
-    }
-    // No errors: apply new image to the cache and use the result.
-    if (input_buffer) {
-      cached_frame_buffer_->PasteFrom(*input_buffer->ToI420().get(),
-                                      partial_desc->offset_x,
-                                      partial_desc->offset_y);
-    }
-  }
-  // Remove partial frame description, as it doesn't make sense after update
-  // is applied.
-  uncompressed_frame->set_partial_frame_description(absl::nullopt);
-  uncompressed_frame->set_video_frame_buffer(
-      I420Buffer::Copy(*cached_frame_buffer_.get()));
-  return true;
-}
-
-void PartialFrameAssembler::Reset() {
-  cached_frame_buffer_ = nullptr;
-}
-
-}  // namespace webrtc
diff --git a/video/partial_frame_assembler.h b/video/partial_frame_assembler.h
deleted file mode 100644
index 9106bf8..0000000
--- a/video/partial_frame_assembler.h
+++ /dev/null
@@ -1,45 +0,0 @@
-/*
- *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#ifndef VIDEO_PARTIAL_FRAME_ASSEMBLER_H_
-#define VIDEO_PARTIAL_FRAME_ASSEMBLER_H_
-
-#include "api/video/i420_buffer.h"
-#include "api/video/video_frame.h"
-
-namespace webrtc {
-
-// Maintains cache of a full resolution frame buffer and applies partial
-// updates to it.
-// This class is not thread-safe.
-class PartialFrameAssembler {
- public:
-  PartialFrameAssembler();
-  ~PartialFrameAssembler();
-
-  // Applies |input_buffer| to the cached buffer and sets buffer for
-  // |uncompresed_frame| to a full updated image.
-  // Returns false on any error. In that case the buffer will be invalidated
-  // and subsequent updates will also return error until full resolution frame
-  // is processed.
-  bool ApplyPartialUpdate(
-      const rtc::scoped_refptr<VideoFrameBuffer>& buffer,
-      VideoFrame* uncompressed_frame,
-      const VideoFrame::PartialFrameDescription* partial_desc);
-
-  // Clears internal buffer.
-  void Reset();
-
- private:
-  rtc::scoped_refptr<I420Buffer> cached_frame_buffer_;
-};
-
-}  // namespace webrtc
-#endif  // VIDEO_PARTIAL_FRAME_ASSEMBLER_H_
diff --git a/video/partial_frame_assembler_unittest.cc b/video/partial_frame_assembler_unittest.cc
deleted file mode 100644
index 25b0f3e..0000000
--- a/video/partial_frame_assembler_unittest.cc
+++ /dev/null
@@ -1,279 +0,0 @@
-/*
- *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#include "video/partial_frame_assembler.h"
-
-#include "api/video/i420_buffer.h"
-#include "api/video/video_frame.h"
-#include "test/gmock.h"
-#include "test/gtest.h"
-
-namespace webrtc {
-namespace {
-
-constexpr uint8_t kCol1 = 100;
-constexpr uint8_t kCol2 = 200;
-
-constexpr int kWidth = 640;
-constexpr int kHeight = 480;
-
-rtc::scoped_refptr<I420Buffer> CreatePicture(int width,
-                                             int height,
-                                             uint8_t data) {
-  rtc::scoped_refptr<I420Buffer> buf = I420Buffer::Create(width, height);
-  for (int row = 0; row < height; ++row) {
-    for (int col = 0; col < width; ++col) {
-      int pos_y = row * buf->StrideY() + col;
-      int pos_u = row / 2 * buf->StrideU() + col / 2;
-      int pos_v = row / 2 * buf->StrideV() + col / 2;
-      buf->MutableDataY()[pos_y] = data;
-      buf->MutableDataU()[pos_u] = data;
-      buf->MutableDataV()[pos_v] = data;
-    }
-  }
-  return buf;
-}
-
-VideoFrame CreateFrame(rtc::scoped_refptr<I420Buffer> buf) {
-  VideoFrame frame = VideoFrame(buf, VideoRotation::kVideoRotation_0, 0);
-  frame.set_cache_buffer_for_partial_updates(true);
-  return frame;
-}
-
-bool TestPictureWithOneRect(rtc::scoped_refptr<I420BufferInterface> buf,
-                            int offset_x,
-                            int offset_y,
-                            int rect_width,
-                            int rect_height,
-                            uint8_t in_rect_data,
-                            uint8_t out_rect_data) {
-  for (int row = 0; row < buf->height(); ++row) {
-    for (int col = 0; col < buf->width(); ++col) {
-      int pos_y = row * buf->StrideY() + col;
-      int pos_u = row / 2 * buf->StrideU() + col / 2;
-      int pos_v = row / 2 * buf->StrideV() + col / 2;
-      uint8_t y = buf->DataY()[pos_y];
-      uint8_t u = buf->DataU()[pos_u];
-      uint8_t v = buf->DataV()[pos_v];
-      bool in_rect = col >= offset_x && col < offset_x + rect_width &&
-                     row >= offset_y && row < offset_y + rect_height;
-      uint8_t expected_data = in_rect ? in_rect_data : out_rect_data;
-      if (y != expected_data || u != expected_data || v != expected_data)
-        return false;
-    }
-  }
-  return true;
-}
-
-TEST(PartialFrameAssembler, FullPictureUpdates) {
-  PartialFrameAssembler decompressor;
-
-  // Full pic.
-  auto full_pic1 = CreatePicture(kWidth, kHeight, kCol1);
-  VideoFrame frame1 = CreateFrame(full_pic1);
-
-  // Full pic.
-  auto full_pic2 = CreatePicture(kWidth, kHeight, kCol2);
-  VideoFrame frame2 = CreateFrame(full_pic2);
-
-  EXPECT_TRUE(
-      decompressor.ApplyPartialUpdate(full_pic1.get(), &frame1, nullptr));
-  EXPECT_TRUE(TestPictureWithOneRect(frame1.video_frame_buffer()->ToI420(), 0,
-                                     0, -1, -1, kCol1, kCol1));
-
-  EXPECT_TRUE(
-      decompressor.ApplyPartialUpdate(full_pic2.get(), &frame2, nullptr));
-  EXPECT_TRUE(TestPictureWithOneRect(frame2.video_frame_buffer()->ToI420(), 0,
-                                     0, -1, -1, kCol2, kCol2));
-}
-
-TEST(PartialFrameAssembler, PartialUpdateFirstFails) {
-  PartialFrameAssembler decompressor;
-
-  // Partial update.
-  auto full_pic1 = CreatePicture(20, 20, kCol1);
-  VideoFrame::PartialFrameDescription desc1{0, 0};
-  VideoFrame frame1 = CreateFrame(full_pic1);
-
-  EXPECT_FALSE(
-      decompressor.ApplyPartialUpdate(full_pic1.get(), &frame1, &desc1));
-}
-
-TEST(PartialFrameAssembler, PartialUpdate) {
-  PartialFrameAssembler decompressor;
-
-  // Full pic.
-  auto full_pic1 = CreatePicture(kWidth, kHeight, kCol1);
-  VideoFrame frame1 = CreateFrame(full_pic1);
-
-  // Partial pic update.
-  auto full_pic2 = CreatePicture(10, 20, kCol2);
-  VideoFrame::PartialFrameDescription desc2{30, 40};
-  VideoFrame frame2 = CreateFrame(full_pic2);
-
-  EXPECT_TRUE(
-      decompressor.ApplyPartialUpdate(full_pic1.get(), &frame1, nullptr));
-  EXPECT_TRUE(TestPictureWithOneRect(frame1.video_frame_buffer()->ToI420(), 0,
-                                     0, -1, -1, kCol1, kCol1));
-
-  EXPECT_TRUE(
-      decompressor.ApplyPartialUpdate(full_pic2.get(), &frame2, &desc2));
-  EXPECT_TRUE(TestPictureWithOneRect(frame2.video_frame_buffer()->ToI420(), 30,
-                                     40, 10, 20, kCol2, kCol1));
-}
-
-TEST(PartialFrameAssembler, ProcessesUnchangedUpdate) {
-  PartialFrameAssembler decompressor;
-
-  auto full_pic1 = CreatePicture(kWidth, kHeight, kCol1);
-  VideoFrame frame1 = CreateFrame(full_pic1);
-
-  // Partial pic update.
-  auto full_pic2 = CreatePicture(10, 20, kCol2);
-  VideoFrame::PartialFrameDescription desc2{30, 40};
-  VideoFrame frame2 = CreateFrame(full_pic2);
-
-  // Empty update.
-  VideoFrame::PartialFrameDescription desc3{0, 0};
-  VideoFrame frame3 = CreateFrame(nullptr);
-
-  EXPECT_TRUE(
-      decompressor.ApplyPartialUpdate(full_pic1.get(), &frame1, nullptr));
-
-  EXPECT_TRUE(
-      decompressor.ApplyPartialUpdate(full_pic2.get(), &frame2, &desc2));
-
-  EXPECT_TRUE(decompressor.ApplyPartialUpdate(nullptr, &frame3, &desc3));
-}
-
-TEST(PartialFrameAssembler, PartialUpdateFailsForOddXOffset) {
-  PartialFrameAssembler decompressor;
-
-  // Full pic.
-  auto full_pic1 = CreatePicture(kWidth, kHeight, kCol1);
-  VideoFrame frame1 = CreateFrame(full_pic1);
-
-  // Partial pic update.
-  auto full_pic2 = CreatePicture(10, 20, kCol2);
-  // Offset is odd.
-  VideoFrame::PartialFrameDescription desc2{31, 40};
-  VideoFrame frame2 = CreateFrame(full_pic2);
-
-  EXPECT_TRUE(
-      decompressor.ApplyPartialUpdate(full_pic1.get(), &frame1, nullptr));
-
-  EXPECT_FALSE(
-      decompressor.ApplyPartialUpdate(full_pic2.get(), &frame2, &desc2));
-}
-
-TEST(PartialFrameAssembler, PartialUpdateFailsForOddYOffset) {
-  PartialFrameAssembler decompressor;
-
-  // Full pic.
-  auto full_pic1 = CreatePicture(kWidth, kHeight, kCol1);
-  VideoFrame frame1 = CreateFrame(full_pic1);
-
-  // Partial pic update.
-  auto full_pic2 = CreatePicture(10, 20, kCol2);
-  // Offset is odd.
-  VideoFrame::PartialFrameDescription desc2{30, 41};
-  VideoFrame frame2 = CreateFrame(full_pic2);
-
-  EXPECT_TRUE(
-      decompressor.ApplyPartialUpdate(full_pic1.get(), &frame1, nullptr));
-
-  EXPECT_FALSE(
-      decompressor.ApplyPartialUpdate(full_pic2.get(), &frame2, &desc2));
-}
-
-TEST(PartialFrameAssembler, PartialUpdateFailsForOddWidth) {
-  PartialFrameAssembler decompressor;
-
-  // Full pic.
-  auto full_pic1 = CreatePicture(kWidth, kHeight, kCol1);
-  VideoFrame frame1 = CreateFrame(full_pic1);
-
-  // Partial pic update. Odd width.
-  auto full_pic2 = CreatePicture(11, 20, kCol2);
-  VideoFrame::PartialFrameDescription desc2{30, 40};
-  VideoFrame frame2 = CreateFrame(full_pic2);
-
-  EXPECT_TRUE(
-      decompressor.ApplyPartialUpdate(full_pic1.get(), &frame1, nullptr));
-
-  EXPECT_FALSE(
-      decompressor.ApplyPartialUpdate(full_pic2.get(), &frame2, &desc2));
-}
-
-TEST(PartialFrameAssembler, PartialUpdateWorksForOddWidthAtTheEnd) {
-  PartialFrameAssembler decompressor;
-
-  // Full pic. Odd resolution.
-  auto full_pic1 = CreatePicture(kWidth + 1, kHeight + 1, kCol1);
-  VideoFrame frame1 = CreateFrame(full_pic1);
-
-  // Partial pic update. Odd width.
-  auto full_pic2 = CreatePicture(11, 11, kCol2);
-  VideoFrame::PartialFrameDescription desc2{kWidth + 1 - 11, kHeight + 1 - 11};
-  VideoFrame frame2 = CreateFrame(full_pic2);
-
-  EXPECT_TRUE(
-      decompressor.ApplyPartialUpdate(full_pic1.get(), &frame1, nullptr));
-
-  EXPECT_TRUE(
-      decompressor.ApplyPartialUpdate(full_pic2.get(), &frame2, &desc2));
-}
-
-TEST(PartialFrameAssembler, PartialUpdateFailsForOddNotAtEnd) {
-  PartialFrameAssembler decompressor;
-
-  // Full pic. Odd resolution.
-  auto full_pic1 = CreatePicture(kWidth + 1, kHeight + 1, kCol1);
-  VideoFrame frame1 = CreateFrame(full_pic1);
-
-  // Partial pic update. Odd width.
-  auto full_pic2 = CreatePicture(11, 11, kCol2);
-  VideoFrame::PartialFrameDescription desc2{kWidth + 1 - 11, kHeight + 1 - 20};
-  VideoFrame frame2 = CreateFrame(full_pic2);
-
-  EXPECT_TRUE(
-      decompressor.ApplyPartialUpdate(full_pic1.get(), &frame1, nullptr));
-
-  EXPECT_FALSE(
-      decompressor.ApplyPartialUpdate(full_pic2.get(), &frame2, &desc2));
-}
-
-TEST(PartialFrameAssembler, FullPictureUpdatesCanChangeResolution) {
-  PartialFrameAssembler decompressor;
-
-  // Full pic.
-  auto full_pic1 = CreatePicture(kWidth, kHeight, kCol1);
-  VideoFrame frame1 = CreateFrame(full_pic1);
-
-  // Full pic.
-  auto full_pic2 = CreatePicture(kWidth + 100, kHeight + 100, kCol2);
-  VideoFrame frame2 = CreateFrame(full_pic2);
-
-  EXPECT_TRUE(
-      decompressor.ApplyPartialUpdate(full_pic1.get(), &frame1, nullptr));
-  EXPECT_TRUE(TestPictureWithOneRect(frame1.video_frame_buffer()->ToI420(), 0,
-                                     0, -1, -1, kCol1, kCol1));
-
-  EXPECT_EQ(frame1.video_frame_buffer()->width(), kWidth);
-  EXPECT_EQ(frame1.video_frame_buffer()->height(), kHeight);
-
-  EXPECT_TRUE(
-      decompressor.ApplyPartialUpdate(full_pic2.get(), &frame2, nullptr));
-  EXPECT_EQ(frame2.video_frame_buffer()->width(), kWidth + 100);
-  EXPECT_EQ(frame2.video_frame_buffer()->height(), kHeight + 100);
-}
-
-}  // namespace
-}  // namespace webrtc