Introduce a client minimum picture pool size

content/common/gpu/media/v4l2_video_decode_accelerator.cc

Index: content/common/gpu/media/v4l2_video_decode_accelerator.cc
diff --git a/content/common/gpu/media/v4l2_video_decode_accelerator.cc b/content/common/gpu/media/v4l2_video_decode_accelerator.cc
index dfd0866e47d77748e1eb6cb95a695d27c5a6c9e4..0f251930a9431f2d8a4a2bf9693826674b492e93 100644
--- a/content/common/gpu/media/v4l2_video_decode_accelerator.cc
+++ b/content/common/gpu/media/v4l2_video_decode_accelerator.cc
@@ -192,6 +192,7 @@ V4L2VideoDecodeAccelerator::V4L2VideoDecodeAccelerator(
       egl_context_(egl_context),
       video_profile_(media::VIDEO_CODEC_PROFILE_UNKNOWN),
       output_format_fourcc_(0),
+      min_picture_count_(0),
       weak_this_factory_(this) {
   weak_this_ = weak_this_factory_.GetWeakPtr();
 }
@@ -210,6 +211,7 @@ V4L2VideoDecodeAccelerator::~V4L2VideoDecodeAccelerator() {
 }
 
 bool V4L2VideoDecodeAccelerator::Initialize(media::VideoCodecProfile profile,
+                                            uint32_t min_picture_count,
                                             Client* client) {
   DVLOG(3) << "Initialize()";
   DCHECK(child_task_runner_->BelongsToCurrentThread());
@@ -239,6 +241,7 @@ bool V4L2VideoDecodeAccelerator::Initialize(media::VideoCodecProfile profile,
       return false;
   };
   video_profile_ = profile;
+  min_picture_count_ = min_picture_count;
 
   if (egl_display_ == EGL_NO_DISPLAY) {
     LOG(ERROR) << "Initialize(): could not get EGLDisplay";
@@ -1836,7 +1839,9 @@ bool V4L2VideoDecodeAccelerator::CreateOutputBuffers() {
   // Allocate the output buffers.
   struct v4l2_requestbuffers reqbufs;
   memset(&reqbufs, 0, sizeof(reqbufs));
-  reqbufs.count  = output_dpb_size_ + kDpbOutputBufferExtraCount;
+  reqbufs.count  = std::max(min_picture_count_,
+                            static_cast<uint32_t>(
+                                output_dpb_size_ + kDpbOutputBufferExtraCount));
   reqbufs.type   = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
   reqbufs.memory = V4L2_MEMORY_MMAP;
   IOCTL_OR_ERROR_RETURN_FALSE(VIDIOC_REQBUFS, &reqbufs);