Support external buffer import in VDA interface and add a V4L2SVDA impl.

content/common/gpu/media/v4l2_slice_video_decode_accelerator.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <errno.h>
 #include <fcntl.h>
 #include <linux/videodev2.h>
 #include <poll.h>
 #include <string.h>
 #include <sys/eventfd.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/callback_helpers.h"
 #include "base/command_line.h"
 #include "base/macros.h"
+#include "base/memory/ptr_util.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/strings/stringprintf.h"
 #include "content/common/gpu/media/shared_memory_region.h"
 #include "content/common/gpu/media/v4l2_slice_video_decode_accelerator.h"
 #include "media/base/bind_to_current_loop.h"
 #include "media/base/media_switches.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/scoped_binders.h"
 
 #define LOGF(level) LOG(level) << __FUNCTION__ << "(): "
@@ skipping 125 matching lines @@
       address(nullptr),
       length(0),
       bytes_used(0),
       at_device(false) {
 }
 
 V4L2SliceVideoDecodeAccelerator::OutputRecord::OutputRecord()
     : at_device(false),
       at_client(false),
       picture_id(-1),
+      texture_id(0),
       egl_image(EGL_NO_IMAGE_KHR),
       egl_sync(EGL_NO_SYNC_KHR),
-      cleared(false) {
-}
+      cleared(false) {}
 
 struct V4L2SliceVideoDecodeAccelerator::BitstreamBufferRef {
   BitstreamBufferRef(
       base::WeakPtr<VideoDecodeAccelerator::Client>& client,
       const scoped_refptr<base::SingleThreadTaskRunner>& client_task_runner,
       SharedMemoryRegion* shm,
       int32_t input_id);
   ~BitstreamBufferRef();
   const base::WeakPtr<VideoDecodeAccelerator::Client> client;
   const scoped_refptr<base::SingleThreadTaskRunner> client_task_runner;
@@ skipping 209 matching lines @@
       device_(device),
       decoder_thread_("V4L2SliceVideoDecodeAcceleratorThread"),
       device_poll_thread_("V4L2SliceVideoDecodeAcceleratorDevicePollThread"),
       input_streamon_(false),
       input_buffer_queued_count_(0),
       output_streamon_(false),
       output_buffer_queued_count_(0),
       video_profile_(media::VIDEO_CODEC_PROFILE_UNKNOWN),
       output_format_fourcc_(0),
       state_(kUninitialized),
+      output_mode_(Config::OutputMode::ALLOCATE),
       decoder_flushing_(false),
       decoder_resetting_(false),
       surface_set_change_pending_(false),
       picture_clearing_count_(0),
-      pictures_assigned_(false, false),
       egl_display_(egl_display),
       get_gl_context_cb_(get_gl_context_cb),
       make_context_current_cb_(make_context_current_cb),
       weak_this_factory_(this) {
   weak_this_ = weak_this_factory_.GetWeakPtr();
 }
 
 V4L2SliceVideoDecodeAccelerator::~V4L2SliceVideoDecodeAccelerator() {
   DVLOGF(2);
 
@@ skipping 18 matching lines @@
     client_ptr_factory_.reset();
   }
 }
 
 bool V4L2SliceVideoDecodeAccelerator::Initialize(const Config& config,
                                                  Client* client) {
   DVLOGF(3) << "profile: " << config.profile;
   DCHECK(child_task_runner_->BelongsToCurrentThread());
   DCHECK_EQ(state_, kUninitialized);
 
-  if (get_gl_context_cb_.is_null() || make_context_current_cb_.is_null()) {
-    NOTREACHED() << "GL callbacks are required for this VDA";
+  if (!device_->SupportsDecodeProfileForV4L2PixelFormats(
+          config.profile, arraysize(supported_input_fourccs_),
+          supported_input_fourccs_)) {
+    DVLOGF(1) << "unsupported profile " << config.profile;
     return false;
   }
 
   if (config.is_encrypted) {
     NOTREACHED() << "Encrypted streams are not supported for this VDA";
     return false;
   }
 
-  if (!device_->SupportsDecodeProfileForV4L2PixelFormats(
-          config.profile, arraysize(supported_input_fourccs_),
-          supported_input_fourccs_)) {
-    DVLOGF(1) << "unsupported profile " << config.profile;
+  if (config.output_mode != Config::OutputMode::ALLOCATE &&
+      config.output_mode != Config::OutputMode::IMPORT) {
+    NOTREACHED() << "Only ALLOCATE and IMPORT OutputModes are supported";
     return false;
   }
 
   client_ptr_factory_.reset(
       new base::WeakPtrFactory<VideoDecodeAccelerator::Client>(client));
   client_ = client_ptr_factory_->GetWeakPtr();
   // If we haven't been set up to decode on separate thread via
   // TryToSetupDecodeOnSeparateThread(), use the main thread/client for
   // decode tasks.
   if (!decode_task_runner_) {
@@ skipping 20 matching lines @@
   // TODO(posciak): This needs to be queried once supported.
   input_planes_count_ = 1;
   output_planes_count_ = 1;
 
   if (egl_display_ == EGL_NO_DISPLAY) {
     LOG(ERROR) << "Initialize(): could not get EGLDisplay";
     return false;
   }
 
   // We need the context to be initialized to query extensions.
-  if (!make_context_current_cb_.Run()) {
-    LOG(ERROR) << "Initialize(): could not make context current";
-    return false;
-  }
+  if (!make_context_current_cb_.is_null()) {
+    if (!make_context_current_cb_.Run()) {
+      LOG(ERROR) << "Initialize(): could not make context current";
+      return false;
+    }
 
-  if (!gfx::g_driver_egl.ext.b_EGL_KHR_fence_sync) {
-    LOG(ERROR) << "Initialize(): context does not have EGL_KHR_fence_sync";
-    return false;
+    if (!gfx::g_driver_egl.ext.b_EGL_KHR_fence_sync) {
+      LOG(ERROR) << "Initialize(): context does not have EGL_KHR_fence_sync";
+      return false;
+    }
+  } else {
+    DVLOG(1) << "No GL callbacks provided, initializing without GL support";
   }
 
   // Capabilities check.
   struct v4l2_capability caps;
   const __u32 kCapsRequired = V4L2_CAP_VIDEO_M2M_MPLANE | V4L2_CAP_STREAMING;
   IOCTL_OR_ERROR_RETURN_FALSE(VIDIOC_QUERYCAP, &caps);
   if ((caps.capabilities & kCapsRequired) != kCapsRequired) {
     LOG(ERROR) << "Initialize(): ioctl() failed: VIDIOC_QUERYCAP"
                   ", caps check failed: 0x" << std::hex << caps.capabilities;
     return false;
   }
 
   if (!SetupFormats())
     return false;
 
   if (!decoder_thread_.Start()) {
     DLOG(ERROR) << "Initialize(): device thread failed to start";
     return false;
   }
   decoder_thread_task_runner_ = decoder_thread_.task_runner();
 
   state_ = kInitialized;
+  output_mode_ = config.output_mode;
 
   // InitializeTask will NOTIFY_ERROR on failure.
   decoder_thread_task_runner_->PostTask(
       FROM_HERE, base::Bind(&V4L2SliceVideoDecodeAccelerator::InitializeTask,
                             base::Unretained(this)));
 
   DVLOGF(1) << "V4L2SliceVideoDecodeAccelerator initialized";
   return true;
 }
 
@@ skipping 12 matching lines @@
 
 void V4L2SliceVideoDecodeAccelerator::Destroy() {
   DVLOGF(3);
   DCHECK(child_task_runner_->BelongsToCurrentThread());
 
   if (decoder_thread_.IsRunning()) {
     decoder_thread_task_runner_->PostTask(
         FROM_HERE, base::Bind(&V4L2SliceVideoDecodeAccelerator::DestroyTask,
                               base::Unretained(this)));
 
-    // Wake up decoder thread in case we are waiting in CreateOutputBuffers
-    // for client to provide pictures. Since this is Destroy, we won't be
-    // getting them anymore (AssignPictureBuffers won't be called).
-    pictures_assigned_.Signal();
-
     // Wait for tasks to finish/early-exit.
     decoder_thread_.Stop();
   }
 
   delete this;
   DVLOGF(3) << "Destroyed";
 }
 
 void V4L2SliceVideoDecodeAccelerator::DestroyTask() {
   DVLOGF(3);
@@ skipping 181 matching lines @@
   DVLOGF(3) << "buffer_count=" << num_pictures
             << ", visible size=" << visible_size_.ToString()
             << ", coded size=" << coded_size_.ToString();
 
   child_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&VideoDecodeAccelerator::Client::ProvidePictureBuffers,
                  client_, num_pictures, 1, coded_size_,
                  device_->GetTextureTarget()));
 
-  // Wait for the client to call AssignPictureBuffers() on the Child thread.
-  // We do this, because if we continue decoding without finishing buffer
-  // allocation, we may end up Resetting before AssignPictureBuffers arrives,
-  // resulting in unnecessary complications and subtle bugs.
-  pictures_assigned_.Wait();
-
+  // Go into kAwaitingPictureBuffers to prevent us from doing any more decoding
+  // or event handling while we are waiting for AssignPictureBuffers(). Not
+  // having Pictures available would not have prevented us from making decoding
+  // progress entirely e.g. in the case of H.264 where we could further decode
+  // non-slice NALUs and could even get another resolution change before we were
+  // done with this one. After we get the buffers, we'll go back into kIdle and
+  // kick off further event processing, and eventually go back into kDecoding
+  // once no more events are pending (if any).
+  state_ = kAwaitingPictureBuffers;
   return true;
 }
 
 void V4L2SliceVideoDecodeAccelerator::DestroyInputBuffers() {
   DVLOGF(3);
   DCHECK(decoder_thread_task_runner_->BelongsToCurrentThread() ||
          !decoder_thread_.IsRunning());
   DCHECK(!input_streamon_);
 
   for (auto& input_record : input_buffer_map_) {
     if (input_record.address != nullptr)
       device_->Munmap(input_record.address, input_record.length);
   }
 
   struct v4l2_requestbuffers reqbufs;
   memset(&reqbufs, 0, sizeof(reqbufs));
   reqbufs.count = 0;
   reqbufs.type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
   reqbufs.memory = V4L2_MEMORY_MMAP;
   IOCTL_OR_LOG_ERROR(VIDIOC_REQBUFS, &reqbufs);
 
   input_buffer_map_.clear();
   free_input_buffers_.clear();
 }
 
 void V4L2SliceVideoDecodeAccelerator::DismissPictures(
-    std::vector<int32_t> picture_buffer_ids,
+    const std::vector<int32_t>& picture_buffer_ids,
     base::WaitableEvent* done) {
   DVLOGF(3);
   DCHECK(child_task_runner_->BelongsToCurrentThread());
 
   for (auto picture_buffer_id : picture_buffer_ids) {
     DVLOGF(1) << "dismissing PictureBuffer id=" << picture_buffer_id;
     client_->DismissPictureBuffer(picture_buffer_id);
   }
 
   done->Signal();
@@ skipping 93 matching lines @@
   DVLOGF(3);
   DCHECK(decoder_thread_task_runner_->BelongsToCurrentThread());
 
   struct v4l2_buffer dqbuf;
   struct v4l2_plane planes[VIDEO_MAX_PLANES];
   while (input_buffer_queued_count_ > 0) {
     DCHECK(input_streamon_);
     memset(&dqbuf, 0, sizeof(dqbuf));
     memset(&planes, 0, sizeof(planes));
     dqbuf.type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
-    dqbuf.memory = V4L2_MEMORY_USERPTR;
+    dqbuf.memory = V4L2_MEMORY_MMAP;
     dqbuf.m.planes = planes;
     dqbuf.length = input_planes_count_;
     if (device_->Ioctl(VIDIOC_DQBUF, &dqbuf) != 0) {
       if (errno == EAGAIN) {
         // EAGAIN if we're just out of buffers to dequeue.
         break;
       }
       PLOG(ERROR) << "ioctl() failed: VIDIOC_DQBUF";
       NOTIFY_ERROR(PLATFORM_FAILURE);
       return;
     }
     InputRecord& input_record = input_buffer_map_[dqbuf.index];
     DCHECK(input_record.at_device);
     input_record.at_device = false;
     ReuseInputBuffer(dqbuf.index);
     input_buffer_queued_count_--;
     DVLOGF(4) << "Dequeued input=" << dqbuf.index
               << " count: " << input_buffer_queued_count_;
   }
 
   while (output_buffer_queued_count_ > 0) {
     DCHECK(output_streamon_);
     memset(&dqbuf, 0, sizeof(dqbuf));
     memset(&planes, 0, sizeof(planes));
     dqbuf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
-    dqbuf.memory = V4L2_MEMORY_MMAP;
+    dqbuf.memory =
+        (output_mode_ == Config::OutputMode::ALLOCATE ? V4L2_MEMORY_MMAP
+                                                      : V4L2_MEMORY_DMABUF);
     dqbuf.m.planes = planes;
     dqbuf.length = output_planes_count_;
     if (device_->Ioctl(VIDIOC_DQBUF, &dqbuf) != 0) {
       if (errno == EAGAIN) {
         // EAGAIN if we're just out of buffers to dequeue.
         break;
       }
       PLOG(ERROR) << "ioctl() failed: VIDIOC_DQBUF";
       NOTIFY_ERROR(PLATFORM_FAILURE);
       return;
@@ skipping 15 matching lines @@
     it->second->SetDecoded();
     surfaces_at_device_.erase(it);
   }
 
   // A frame was decoded, see if we can output it.
   TryOutputSurfaces();
 
   ProcessPendingEventsIfNeeded();
 }
 
+void V4L2SliceVideoDecodeAccelerator::NewEventPending() {
+  // Switch to event processing mode if we are decoding. Otherwise we are either
+  // already in it, or we will potentially switch to it later, after finishing
+  // other tasks.
+  if (state_ == kDecoding)
+    state_ = kIdle;
+
+  ProcessPendingEventsIfNeeded();
+}
+
+bool V4L2SliceVideoDecodeAccelerator::FinishEventProcessing() {
+  DCHECK_EQ(state_, kIdle);
+
+  state_ = kDecoding;
+  ScheduleDecodeBufferTaskIfNeeded();
+
+  return true;
+}
+
 void V4L2SliceVideoDecodeAccelerator::ProcessPendingEventsIfNeeded() {
+  DCHECK(decoder_thread_task_runner_->BelongsToCurrentThread());
+
   // Process pending events, if any, in the correct order.
   // We always first process the surface set change, as it is an internal
   // event from the decoder and interleaving it with external requests would
   // put the decoder in an undefined state.
-  FinishSurfaceSetChangeIfNeeded();
+  using ProcessFunc = bool (V4L2SliceVideoDecodeAccelerator::*)();
+  const ProcessFunc process_functions[] = {
+      &V4L2SliceVideoDecodeAccelerator::FinishSurfaceSetChange,
+      &V4L2SliceVideoDecodeAccelerator::FinishFlush,
+      &V4L2SliceVideoDecodeAccelerator::FinishReset,
+      &V4L2SliceVideoDecodeAccelerator::FinishEventProcessing,
+  };
 
-  // Process external (client) requests.
-  FinishFlushIfNeeded();
-  FinishResetIfNeeded();
+  for (const auto& fn : process_functions) {
+    if (state_ != kIdle)
+      return;
+
+    if (!(this->*fn)())
+      return;
+  }
 }
 
 void V4L2SliceVideoDecodeAccelerator::ReuseInputBuffer(int index) {
   DVLOGF(4) << "Reusing input buffer, index=" << index;
   DCHECK(decoder_thread_task_runner_->BelongsToCurrentThread());
 
   DCHECK_LT(index, static_cast<int>(input_buffer_map_.size()));
   InputRecord& input_record = input_buffer_map_[index];
 
   DCHECK(!input_record.at_device);
@@ skipping 52 matching lines @@
 }
 
 bool V4L2SliceVideoDecodeAccelerator::EnqueueOutputRecord(int index) {
   DVLOGF(3);
   DCHECK_LT(index, static_cast<int>(output_buffer_map_.size()));
 
   // Enqueue an output (VIDEO_CAPTURE) buffer.
   OutputRecord& output_record = output_buffer_map_[index];
   DCHECK(!output_record.at_device);
   DCHECK(!output_record.at_client);
-  DCHECK_NE(output_record.egl_image, EGL_NO_IMAGE_KHR);
   DCHECK_NE(output_record.picture_id, -1);
 
   if (output_record.egl_sync != EGL_NO_SYNC_KHR) {
     // If we have to wait for completion, wait.  Note that
     // free_output_buffers_ is a FIFO queue, so we always wait on the
     // buffer that has been in the queue the longest.
     if (eglClientWaitSyncKHR(egl_display_, output_record.egl_sync, 0,
                              EGL_FOREVER_KHR) == EGL_FALSE) {
       // This will cause tearing, but is safe otherwise.
       DVLOGF(1) << "eglClientWaitSyncKHR failed!";
     }
     if (eglDestroySyncKHR(egl_display_, output_record.egl_sync) != EGL_TRUE) {
       LOGF(ERROR) << "eglDestroySyncKHR failed!";
       NOTIFY_ERROR(PLATFORM_FAILURE);
       return false;
     }
     output_record.egl_sync = EGL_NO_SYNC_KHR;
   }
 
   struct v4l2_buffer qbuf;
   struct v4l2_plane qbuf_planes[VIDEO_MAX_PLANES];
   memset(&qbuf, 0, sizeof(qbuf));
   memset(qbuf_planes, 0, sizeof(qbuf_planes));
   qbuf.index = index;
   qbuf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
-  qbuf.memory = V4L2_MEMORY_MMAP;
+  if (output_mode_ == Config::OutputMode::ALLOCATE) {
+    qbuf.memory = V4L2_MEMORY_MMAP;
+  } else {
+    qbuf.memory = V4L2_MEMORY_DMABUF;
+    DCHECK_EQ(output_planes_count_, output_record.dmabuf_fds.size());
+    for (size_t i = 0; i < output_record.dmabuf_fds.size(); ++i) {
+      DCHECK(output_record.dmabuf_fds[i].is_valid());
+      qbuf_planes[i].m.fd = output_record.dmabuf_fds[i].get();
+    }
+  }
   qbuf.m.planes = qbuf_planes;
   qbuf.length = output_planes_count_;
   IOCTL_OR_ERROR_RETURN_FALSE(VIDIOC_QBUF, &qbuf);
   output_record.at_device = true;
   output_buffer_queued_count_++;
   DVLOGF(4) << "Enqueued output=" << qbuf.index
             << " count: " << output_buffer_queued_count_;
 
   return true;
 }
@@ skipping 205 matching lines @@
         DVLOGF(1) << "Error decoding stream";
         NOTIFY_ERROR(PLATFORM_FAILURE);
         return;
     }
   }
 }
 
 void V4L2SliceVideoDecodeAccelerator::InitiateSurfaceSetChange() {
   DVLOGF(2);
   DCHECK(decoder_thread_task_runner_->BelongsToCurrentThread());
-
   DCHECK_EQ(state_, kDecoding);
-  state_ = kIdle;
 
   DCHECK(!surface_set_change_pending_);
   surface_set_change_pending_ = true;
-
-  FinishSurfaceSetChangeIfNeeded();
+  NewEventPending();
 }
 
-void V4L2SliceVideoDecodeAccelerator::FinishSurfaceSetChangeIfNeeded() {
+bool V4L2SliceVideoDecodeAccelerator::FinishSurfaceSetChange() {
   DVLOGF(2);
   DCHECK(decoder_thread_task_runner_->BelongsToCurrentThread());
 
-  if (!surface_set_change_pending_ || !surfaces_at_device_.empty())
-    return;
+  if (!surface_set_change_pending_)
+    return true;
+
+  if (!surfaces_at_device_.empty())
+    return false;
 
   DCHECK_EQ(state_, kIdle);
   DCHECK(decoder_display_queue_.empty());
   // All output buffers should've been returned from decoder and device by now.
   // The only remaining owner of surfaces may be display (client), and we will
   // dismiss them when destroying output buffers below.
   DCHECK_EQ(free_output_buffers_.size() + surfaces_at_display_.size(),
             output_buffer_map_.size());
 
   // Keep input queue running while we switch outputs.
   if (!StopDevicePoll(true)) {
     NOTIFY_ERROR(PLATFORM_FAILURE);
-    return;
+    return false;
   }
 
   // This will return only once all buffers are dismissed and destroyed.
   // This does not wait until they are displayed however, as display retains
   // references to the buffers bound to textures and will release them
   // after displaying.
   if (!DestroyOutputs(true)) {
     NOTIFY_ERROR(PLATFORM_FAILURE);
-    return;
+    return false;
   }
 
   if (!CreateOutputBuffers()) {
     NOTIFY_ERROR(PLATFORM_FAILURE);
-    return;
+    return false;
   }
 
-  if (!StartDevicePoll()) {
-    NOTIFY_ERROR(PLATFORM_FAILURE);
-    return;
-  }
-
-  DVLOGF(3) << "Surface set change finished";
-
   surface_set_change_pending_ = false;
-  state_ = kDecoding;
-  ScheduleDecodeBufferTaskIfNeeded();
+  DVLOG(3) << "Surface set change finished";
+  return true;
 }
 
 bool V4L2SliceVideoDecodeAccelerator::DestroyOutputs(bool dismiss) {
   DVLOGF(3);
   DCHECK(decoder_thread_task_runner_->BelongsToCurrentThread());
-  std::vector<EGLImageKHR> egl_images_to_destroy;
   std::vector<int32_t> picture_buffers_to_dismiss;
 
   if (output_buffer_map_.empty())
     return true;
 
-  for (auto output_record : output_buffer_map_) {
+  for (const auto& output_record : output_buffer_map_) {
     DCHECK(!output_record.at_device);
 
     if (output_record.egl_sync != EGL_NO_SYNC_KHR) {
       if (eglDestroySyncKHR(egl_display_, output_record.egl_sync) != EGL_TRUE)
         DVLOGF(1) << "eglDestroySyncKHR failed.";
     }
 
     if (output_record.egl_image != EGL_NO_IMAGE_KHR) {
       child_task_runner_->PostTask(
           FROM_HERE,
@@ skipping 57 matching lines @@
   IOCTL_OR_ERROR_RETURN_FALSE(VIDIOC_REQBUFS, &reqbufs);
 
   return true;
 }
 
 void V4L2SliceVideoDecodeAccelerator::AssignPictureBuffers(
     const std::vector<media::PictureBuffer>& buffers) {
   DVLOGF(3);
   DCHECK(child_task_runner_->BelongsToCurrentThread());
 
+  decoder_thread_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&V4L2SliceVideoDecodeAccelerator::AssignPictureBuffersTask,
+                 base::Unretained(this), buffers));
+}
+
+void V4L2SliceVideoDecodeAccelerator::AssignPictureBuffersTask(
+    const std::vector<media::PictureBuffer>& buffers) {
+  DVLOGF(3);
+  DCHECK(decoder_thread_task_runner_->BelongsToCurrentThread());
+  DCHECK_EQ(state_, kAwaitingPictureBuffers);
+
   const uint32_t req_buffer_count = decoder_->GetRequiredNumOfPictures();
 
   if (buffers.size() < req_buffer_count) {
     DLOG(ERROR) << "Failed to provide requested picture buffers. "
                 << "(Got " << buffers.size()
                 << ", requested " << req_buffer_count << ")";
     NOTIFY_ERROR(INVALID_ARGUMENT);
     return;
   }
 
-  gfx::GLContext* gl_context = get_gl_context_cb_.Run();
-  if (!gl_context || !make_context_current_cb_.Run()) {
-    DLOG(ERROR) << "No GL context";
-    NOTIFY_ERROR(PLATFORM_FAILURE);
-    return;
-  }
-
-  gfx::ScopedTextureBinder bind_restore(GL_TEXTURE_EXTERNAL_OES, 0);
-
-  // It's safe to manipulate all the buffer state here, because the decoder
-  // thread is waiting on pictures_assigned_.
-
   // Allocate the output buffers.
   struct v4l2_requestbuffers reqbufs;
   memset(&reqbufs, 0, sizeof(reqbufs));
   reqbufs.count = buffers.size();
   reqbufs.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
-  reqbufs.memory = V4L2_MEMORY_MMAP;
+  reqbufs.memory =
+      (output_mode_ == Config::OutputMode::ALLOCATE ? V4L2_MEMORY_MMAP
+                                                    : V4L2_MEMORY_DMABUF);
   IOCTL_OR_ERROR_RETURN(VIDIOC_REQBUFS, &reqbufs);
 
   if (reqbufs.count != buffers.size()) {
     DLOG(ERROR) << "Could not allocate enough output buffers";
     NOTIFY_ERROR(PLATFORM_FAILURE);
     return;
   }
 
+  DCHECK(free_output_buffers_.empty());
+  DCHECK(output_buffer_map_.empty());
   output_buffer_map_.resize(buffers.size());
-
-  DCHECK(free_output_buffers_.empty());
   for (size_t i = 0; i < output_buffer_map_.size(); ++i) {
     DCHECK(buffers[i].size() == coded_size_);
+    DCHECK_EQ(1u, buffers[i].texture_ids().size());
 
     OutputRecord& output_record = output_buffer_map_[i];
     DCHECK(!output_record.at_device);
     DCHECK(!output_record.at_client);
     DCHECK_EQ(output_record.egl_image, EGL_NO_IMAGE_KHR);
     DCHECK_EQ(output_record.egl_sync, EGL_NO_SYNC_KHR);
     DCHECK_EQ(output_record.picture_id, -1);
+    DCHECK(output_record.dmabuf_fds.empty());
     DCHECK_EQ(output_record.cleared, false);
 
-    DCHECK_LE(1u, buffers[i].texture_ids().size());
-    EGLImageKHR egl_image = device_->CreateEGLImage(
-        egl_display_, gl_context->GetHandle(), buffers[i].texture_ids()[0],
-        buffers[i].size(), i, output_format_fourcc_, output_planes_count_);
-    if (egl_image == EGL_NO_IMAGE_KHR) {
-      LOGF(ERROR) << "Could not create EGLImageKHR";
-      // Ownership of EGLImages allocated in previous iterations of this loop
-      // has been transferred to output_buffer_map_. After we error-out here
-      // the destructor will handle their cleanup.
-      NOTIFY_ERROR(PLATFORM_FAILURE);
-      return;
+    output_record.picture_id = buffers[i].id();
+    output_record.texture_id = buffers[i].texture_ids()[0];
+    // This will remain true until ImportBufferForPicture is called, either by
+    // the client, or by ourselves, if we are allocating.
+    output_record.at_client = true;
+    if (output_mode_ == Config::OutputMode::ALLOCATE) {
+      std::vector<base::ScopedFD> dmabuf_fds =
+          std::move(device_->GetDmabufsForV4L2Buffer(
+              i, output_planes_count_, V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE));
+      if (dmabuf_fds.empty()) {
+        NOTIFY_ERROR(PLATFORM_FAILURE);
+        return;
+      }
+
+      auto passed_dmabuf_fds(base::WrapUnique(
+          new std::vector<base::ScopedFD>(std::move(dmabuf_fds))));
+      ImportBufferForPictureTask(output_record.picture_id,
+                                 std::move(passed_dmabuf_fds));
+    }  // else we'll get triggered via ImportBufferForPicture() from client.
+    DVLOGF(3) << "buffer[" << i << "]: picture_id=" << output_record.picture_id;
+  }
+
+  if (!StartDevicePoll()) {
+    NOTIFY_ERROR(PLATFORM_FAILURE);
+    return;
+  }
+
+  // Put us in kIdle to allow further event processing.
+  // ProcessPendingEventsIfNeeded() will put us back into kDecoding after all
+  // other pending events are processed successfully.
+  state_ = kIdle;
+  ProcessPendingEventsIfNeeded();
+}
+
+void V4L2SliceVideoDecodeAccelerator::CreateEGLImageFor(
+    size_t buffer_index,
+    int32_t picture_buffer_id,
+    std::unique_ptr<std::vector<base::ScopedFD>> passed_dmabuf_fds,
+    GLuint texture_id,
+    const gfx::Size& size,
+    uint32_t fourcc) {
+  DVLOGF(3) << "index=" << buffer_index;
+  DCHECK(child_task_runner_->BelongsToCurrentThread());
+
+  if (get_gl_context_cb_.is_null() || make_context_current_cb_.is_null()) {
+    DLOG(ERROR) << "GL callbacks required for binding to EGLImages";
+    NOTIFY_ERROR(INVALID_ARGUMENT);
+    return;
+  }
+
+  gfx::GLContext* gl_context = get_gl_context_cb_.Run();
+  if (!gl_context || !make_context_current_cb_.Run()) {
+    DLOG(ERROR) << "No GL context";
+    NOTIFY_ERROR(PLATFORM_FAILURE);
+    return;
+  }
+
+  gfx::ScopedTextureBinder bind_restore(GL_TEXTURE_EXTERNAL_OES, 0);
+
+  EGLImageKHR egl_image =
+      device_->CreateEGLImage(egl_display_, gl_context->GetHandle(), texture_id,
+                              size, buffer_index, fourcc, *passed_dmabuf_fds);
+  if (egl_image == EGL_NO_IMAGE_KHR) {
+    LOGF(ERROR) << "Could not create EGLImageKHR,"
+                << " index=" << buffer_index << " texture_id=" << texture_id;
+    NOTIFY_ERROR(PLATFORM_FAILURE);
+    return;
+  }
+
+  decoder_thread_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&V4L2SliceVideoDecodeAccelerator::AssignEGLImage,
+                 base::Unretained(this), buffer_index, picture_buffer_id,
+                 egl_image, base::Passed(&passed_dmabuf_fds)));
+}
+
+void V4L2SliceVideoDecodeAccelerator::AssignEGLImage(
+    size_t buffer_index,
+    int32_t picture_buffer_id,
+    EGLImageKHR egl_image,
+    std::unique_ptr<std::vector<base::ScopedFD>> passed_dmabuf_fds) {
+  DVLOGF(3) << "index=" << buffer_index;
+  DCHECK(decoder_thread_task_runner_->BelongsToCurrentThread());
+
+  // It's possible that while waiting for the EGLImages to be allocated and
+  // assigned, we have already decoded more of the stream and saw another
+  // resolution change. This is a normal situation, in such a case either there
+  // is no output record with this index awaiting an EGLImage to be assigned to
+  // it, or the record is already updated to use a newer PictureBuffer and is
+  // awaiting an EGLImage associated with a different picture_buffer_id. If so,
+  // just discard this image, we will get the one we are waiting for later.
+  if (buffer_index >= output_buffer_map_.size() ||
+      output_buffer_map_[buffer_index].picture_id != picture_buffer_id) {
+    DVLOGF(3) << "Picture set already changed, dropping EGLImage";
+    child_task_runner_->PostTask(
+        FROM_HERE, base::Bind(base::IgnoreResult(&V4L2Device::DestroyEGLImage),
+                              device_, egl_display_, egl_image));
+    return;
+  }
+
+  OutputRecord& output_record = output_buffer_map_[buffer_index];
+  DCHECK_EQ(output_record.egl_image, EGL_NO_IMAGE_KHR);
+  DCHECK_EQ(output_record.egl_sync, EGL_NO_SYNC_KHR);
+  DCHECK(!output_record.at_client);
+  DCHECK(!output_record.at_device);
+
+  output_record.egl_image = egl_image;
+  if (output_mode_ == Config::OutputMode::IMPORT) {
+    DCHECK(output_record.dmabuf_fds.empty());
+    output_record.dmabuf_fds = std::move(*passed_dmabuf_fds);
+  }
+
+  DCHECK_EQ(std::count(free_output_buffers_.begin(), free_output_buffers_.end(),
+                       buffer_index),
+            0);
+  free_output_buffers_.push_back(buffer_index);
+  ScheduleDecodeBufferTaskIfNeeded();
+}
+
+void V4L2SliceVideoDecodeAccelerator::ImportBufferForPicture(
+    int32_t picture_buffer_id,
+    const std::vector<gfx::GpuMemoryBufferHandle>& gpu_memory_buffer_handles) {
+  DVLOGF(3) << "picture_buffer_id=" << picture_buffer_id;
+  DCHECK(child_task_runner_->BelongsToCurrentThread());
+
+  auto passed_dmabuf_fds(base::WrapUnique(new std::vector<base::ScopedFD>()));
+  for (const auto& handle : gpu_memory_buffer_handles) {
+    int fd = -1;
+#if defined(USE_OZONE)
+    fd = handle.native_pixmap_handle.fd.fd;
+#endif
+    DCHECK_NE(fd, -1);
+    passed_dmabuf_fds->push_back(base::ScopedFD(fd));
+  }
+
+  if (output_mode_ != Config::OutputMode::IMPORT) {
+    LOGF(ERROR) << "Cannot import in non-import mode";
+    NOTIFY_ERROR(INVALID_ARGUMENT);
+    return;
+  }
+
+  decoder_thread_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&V4L2SliceVideoDecodeAccelerator::ImportBufferForPictureTask,
+                 base::Unretained(this), picture_buffer_id,
+                 base::Passed(&passed_dmabuf_fds)));
+}
+
+void V4L2SliceVideoDecodeAccelerator::ImportBufferForPictureTask(
+    int32_t picture_buffer_id,
+    std::unique_ptr<std::vector<base::ScopedFD>> passed_dmabuf_fds) {
+  DVLOGF(3) << "picture_buffer_id=" << picture_buffer_id;
+  DCHECK(decoder_thread_task_runner_->BelongsToCurrentThread());
+
+  const auto iter =
+      std::find_if(output_buffer_map_.begin(), output_buffer_map_.end(),
+                   [picture_buffer_id](const OutputRecord& output_record) {
+                     return output_record.picture_id == picture_buffer_id;
+                   });
+  if (iter == output_buffer_map_.end()) {
+    LOGF(ERROR) << "Invalid picture_buffer_id=" << picture_buffer_id;
+    NOTIFY_ERROR(INVALID_ARGUMENT);
+    return;
+  }
+
+  if (!iter->at_client) {
+    LOGF(ERROR) << "Cannot import buffer that not owned by client";
+    NOTIFY_ERROR(INVALID_ARGUMENT);
+    return;
+  }
+
+  size_t index = iter - output_buffer_map_.begin();
+  DCHECK_EQ(std::count(free_output_buffers_.begin(), free_output_buffers_.end(),
+                       index),
+            0);
+
+  DCHECK(!iter->at_device);
+  iter->at_client = false;
+  if (iter->texture_id != 0) {
+    if (iter->egl_image != EGL_NO_IMAGE_KHR) {
+      child_task_runner_->PostTask(
+          FROM_HERE,
+          base::Bind(base::IgnoreResult(&V4L2Device::DestroyEGLImage), device_,
+                     egl_display_, iter->egl_image));
     }
 
-    output_record.egl_image = egl_image;
-    output_record.picture_id = buffers[i].id();
-    free_output_buffers_.push_back(i);
-    DVLOGF(3) << "buffer[" << i << "]: picture_id=" << output_record.picture_id;
-  }
-
-  pictures_assigned_.Signal();
+    child_task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&V4L2SliceVideoDecodeAccelerator::CreateEGLImageFor,
+                   weak_this_, index, picture_buffer_id,
+                   base::Passed(&passed_dmabuf_fds), iter->texture_id,
+                   coded_size_, output_format_fourcc_));
+  } else {
+    // No need for an EGLImage, start using this buffer now.
+    DCHECK_EQ(output_planes_count_, passed_dmabuf_fds->size());
+    iter->dmabuf_fds.swap(*passed_dmabuf_fds);
+    free_output_buffers_.push_back(index);
+    ScheduleDecodeBufferTaskIfNeeded();
+  }
 }
 
 void V4L2SliceVideoDecodeAccelerator::ReusePictureBuffer(
     int32_t picture_buffer_id) {
   DCHECK(child_task_runner_->BelongsToCurrentThread());
   DVLOGF(4) << "picture_buffer_id=" << picture_buffer_id;
 
-  if (!make_context_current_cb_.Run()) {
-    LOGF(ERROR) << "could not make context current";
-    NOTIFY_ERROR(PLATFORM_FAILURE);
-    return;
-  }
-
-  EGLSyncKHR egl_sync =
-      eglCreateSyncKHR(egl_display_, EGL_SYNC_FENCE_KHR, NULL);
-  if (egl_sync == EGL_NO_SYNC_KHR) {
-    LOGF(ERROR) << "eglCreateSyncKHR() failed";
-    NOTIFY_ERROR(PLATFORM_FAILURE);
-    return;
-  }
-
-  std::unique_ptr<EGLSyncKHRRef> egl_sync_ref(
-      new EGLSyncKHRRef(egl_display_, egl_sync));
+  std::unique_ptr<EGLSyncKHRRef> egl_sync_ref;
+
+  if (!make_context_current_cb_.is_null()) {
+    if (!make_context_current_cb_.Run()) {
+      LOGF(ERROR) << "could not make context current";
+      NOTIFY_ERROR(PLATFORM_FAILURE);
+      return;
+    }
+
+    EGLSyncKHR egl_sync =
+        eglCreateSyncKHR(egl_display_, EGL_SYNC_FENCE_KHR, NULL);
+    if (egl_sync == EGL_NO_SYNC_KHR) {
+      LOGF(ERROR) << "eglCreateSyncKHR() failed";
+      NOTIFY_ERROR(PLATFORM_FAILURE);
+      return;
+    }
+
+    egl_sync_ref.reset(new EGLSyncKHRRef(egl_display_, egl_sync));
+  }
+
   decoder_thread_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&V4L2SliceVideoDecodeAccelerator::ReusePictureBufferTask,
                  base::Unretained(this), picture_buffer_id,
                  base::Passed(&egl_sync_ref)));
 }
 
 void V4L2SliceVideoDecodeAccelerator::ReusePictureBufferTask(
     int32_t picture_buffer_id,
     std::unique_ptr<EGLSyncKHRRef> egl_sync_ref) {
@@ skipping 16 matching lines @@
   OutputRecord& output_record = output_buffer_map_[it->second->output_record()];
   if (output_record.at_device || !output_record.at_client) {
     DVLOGF(1) << "picture_buffer_id not reusable";
     NOTIFY_ERROR(INVALID_ARGUMENT);
     return;
   }
 
   DCHECK_EQ(output_record.egl_sync, EGL_NO_SYNC_KHR);
   DCHECK(!output_record.at_device);
   output_record.at_client = false;
-  output_record.egl_sync = egl_sync_ref->egl_sync;
-  // Take ownership of the EGLSync.
-  egl_sync_ref->egl_sync = EGL_NO_SYNC_KHR;
+  if (egl_sync_ref) {
+    output_record.egl_sync = egl_sync_ref->egl_sync;
+    // Take ownership of the EGLSync.
+    egl_sync_ref->egl_sync = EGL_NO_SYNC_KHR;
+  }
+
   surfaces_at_display_.erase(it);
 }
 
 void V4L2SliceVideoDecodeAccelerator::Flush() {
   DVLOGF(3);
   DCHECK(child_task_runner_->BelongsToCurrentThread());
 
   decoder_thread_task_runner_->PostTask(
       FROM_HERE, base::Bind(&V4L2SliceVideoDecodeAccelerator::FlushTask,
                             base::Unretained(this)));
@@ skipping 13 matching lines @@
   }
 
   // No more inputs pending, so just finish flushing here.
   InitiateFlush();
 }
 
 void V4L2SliceVideoDecodeAccelerator::InitiateFlush() {
   DVLOGF(3);
   DCHECK(decoder_thread_task_runner_->BelongsToCurrentThread());
 
-  DCHECK(!decoder_flushing_);
-  DCHECK_EQ(state_, kDecoding);
-  state_ = kIdle;
-
   // This will trigger output for all remaining surfaces in the decoder.
   // However, not all of them may be decoded yet (they would be queued
   // in hardware then).
   if (!decoder_->Flush()) {
     DVLOGF(1) << "Failed flushing the decoder.";
     NOTIFY_ERROR(PLATFORM_FAILURE);
     return;
   }
 
   // Put the decoder in an idle state, ready to resume.
   decoder_->Reset();
 
+  DCHECK(!decoder_flushing_);
   decoder_flushing_ = true;
-
-  decoder_thread_task_runner_->PostTask(
-      FROM_HERE,
-      base::Bind(&V4L2SliceVideoDecodeAccelerator::FinishFlushIfNeeded,
-                 base::Unretained(this)));
+  NewEventPending();
 }
 
-void V4L2SliceVideoDecodeAccelerator::FinishFlushIfNeeded() {
+bool V4L2SliceVideoDecodeAccelerator::FinishFlush() {
   DVLOGF(3);
   DCHECK(decoder_thread_task_runner_->BelongsToCurrentThread());
 
-  if (!decoder_flushing_ || !surfaces_at_device_.empty())
-    return;
+  if (!decoder_flushing_)
+    return true;
+
+  if (!surfaces_at_device_.empty())
+    return false;
 
   DCHECK_EQ(state_, kIdle);
 
   // At this point, all remaining surfaces are decoded and dequeued, and since
   // we have already scheduled output for them in InitiateFlush(), their
   // respective PictureReady calls have been posted (or they have been queued on
   // pending_picture_ready_). So at this time, once we SendPictureReady(),
   // we will have all remaining PictureReady() posted to the client and we
   // can post NotifyFlushDone().
   DCHECK(decoder_display_queue_.empty());
 
   // Decoder should have already returned all surfaces and all surfaces are
   // out of hardware. There can be no other owners of input buffers.
   DCHECK_EQ(free_input_buffers_.size(), input_buffer_map_.size());
 
   SendPictureReady();
 
+  decoder_flushing_ = false;
+  DVLOGF(3) << "Flush finished";
+
   child_task_runner_->PostTask(FROM_HERE,
                                base::Bind(&Client::NotifyFlushDone, client_));
 
-  decoder_flushing_ = false;
-
-  DVLOGF(3) << "Flush finished";
-  state_ = kDecoding;
-  ScheduleDecodeBufferTaskIfNeeded();
+  return true;
 }
 
 void V4L2SliceVideoDecodeAccelerator::Reset() {
   DVLOGF(3);
   DCHECK(child_task_runner_->BelongsToCurrentThread());
 
   decoder_thread_task_runner_->PostTask(
       FROM_HERE, base::Bind(&V4L2SliceVideoDecodeAccelerator::ResetTask,
                             base::Unretained(this)));
 }
 
 void V4L2SliceVideoDecodeAccelerator::ResetTask() {
   DVLOGF(3);
   DCHECK(decoder_thread_task_runner_->BelongsToCurrentThread());
 
   if (decoder_resetting_) {
     // This is a bug in the client, multiple Reset()s before NotifyResetDone()
     // are not allowed.
     NOTREACHED() << "Client should not be requesting multiple Reset()s";
     return;
   }
 
-  DCHECK_EQ(state_, kDecoding);
-  state_ = kIdle;
-
   // Put the decoder in an idle state, ready to resume.
   decoder_->Reset();
 
-  decoder_resetting_ = true;
-
   // Drop all remaining inputs.
   decoder_current_bitstream_buffer_.reset();
   while (!decoder_input_queue_.empty())
     decoder_input_queue_.pop();
 
-  FinishResetIfNeeded();
+  decoder_resetting_ = true;
+  NewEventPending();
 }
 
-void V4L2SliceVideoDecodeAccelerator::FinishResetIfNeeded() {
+bool V4L2SliceVideoDecodeAccelerator::FinishReset() {
   DVLOGF(3);
   DCHECK(decoder_thread_task_runner_->BelongsToCurrentThread());
 
-  if (!decoder_resetting_ || !surfaces_at_device_.empty())
-    return;
+  if (!decoder_resetting_)
+    return true;
+
+  if (!surfaces_at_device_.empty())
+    return false;
 
   DCHECK_EQ(state_, kIdle);
   DCHECK(!decoder_flushing_);
   SendPictureReady();
 
   // Drop any pending outputs.
   while (!decoder_display_queue_.empty())
     decoder_display_queue_.pop();
 
   // At this point we can have no input buffers in the decoder, because we
   // Reset()ed it in ResetTask(), and have not scheduled any new Decode()s
   // having been in kIdle since. We don't have any surfaces in the HW either -
   // we just checked that surfaces_at_device_.empty(), and inputs are tied
   // to surfaces. Since there can be no other owners of input buffers, we can
   // simply mark them all as available.
   DCHECK_EQ(input_buffer_queued_count_, 0);
   free_input_buffers_.clear();
   for (size_t i = 0; i < input_buffer_map_.size(); ++i) {
     DCHECK(!input_buffer_map_[i].at_device);
     ReuseInputBuffer(i);
   }
 
   decoder_resetting_ = false;
+  DVLOGF(3) << "Reset finished";
 
   child_task_runner_->PostTask(FROM_HERE,
                                base::Bind(&Client::NotifyResetDone, client_));
 
-  DVLOGF(3) << "Reset finished";
-
-  state_ = kDecoding;
-  ScheduleDecodeBufferTaskIfNeeded();
+  return true;
 }
 
 void V4L2SliceVideoDecodeAccelerator::SetErrorState(Error error) {
   // We can touch decoder_state_ only if this is the decoder thread or the
   // decoder thread isn't running.
   if (decoder_thread_.IsRunning() &&
       !decoder_thread_task_runner_->BelongsToCurrentThread()) {
     decoder_thread_task_runner_->PostTask(
         FROM_HERE, base::Bind(&V4L2SliceVideoDecodeAccelerator::SetErrorState,
                               base::Unretained(this), error));
@@ skipping 699 matching lines @@
   OutputRecord& output_record =
       output_buffer_map_[dec_surface->output_record()];
 
   bool inserted =
       surfaces_at_display_.insert(std::make_pair(output_record.picture_id,
                                                  dec_surface)).second;
   DCHECK(inserted);
 
   DCHECK(!output_record.at_client);
   DCHECK(!output_record.at_device);
-  DCHECK_NE(output_record.egl_image, EGL_NO_IMAGE_KHR);
   DCHECK_NE(output_record.picture_id, -1);
   output_record.at_client = true;
 
   // TODO(posciak): Use visible size from decoder here instead
   // (crbug.com/402760). Passing (0, 0) results in the client using the
   // visible size extracted from the container instead.
   media::Picture picture(output_record.picture_id, dec_surface->bitstream_id(),
                          gfx::Rect(0, 0), false);
   DVLOGF(3) << dec_surface->ToString()
             << ", bitstream_id: " << picture.bitstream_buffer_id()
@@ skipping 85 matching lines @@
 }
 
 bool V4L2SliceVideoDecodeAccelerator::TryToSetupDecodeOnSeparateThread(
     const base::WeakPtr<Client>& decode_client,
     const scoped_refptr<base::SingleThreadTaskRunner>& decode_task_runner) {
   decode_client_ = decode_client_;
   decode_task_runner_ = decode_task_runner;
   return true;
 }
 
+media::VideoPixelFormat V4L2SliceVideoDecodeAccelerator::GetOutputFormat()
+    const {
+  return V4L2Device::V4L2PixFmtToVideoPixelFormat(output_format_fourcc_);
+}
+
 // static
 media::VideoDecodeAccelerator::SupportedProfiles
 V4L2SliceVideoDecodeAccelerator::GetSupportedProfiles() {
   scoped_refptr<V4L2Device> device = V4L2Device::Create(V4L2Device::kDecoder);
   if (!device)
     return SupportedProfiles();
 
   return device->GetSupportedDecodeProfiles(arraysize(supported_input_fourccs_),
                                             supported_input_fourccs_);
 }
 
 }  // namespace content