Introduce a client minimum picture pool size

content/common/gpu/media/vaapi_video_decode_accelerator.cc

Index: content/common/gpu/media/vaapi_video_decode_accelerator.cc
diff --git a/content/common/gpu/media/vaapi_video_decode_accelerator.cc b/content/common/gpu/media/vaapi_video_decode_accelerator.cc
index 2d638cbcb565ee632b7db0947df44818c9e94f44..d8c3b31bf9217fb21035886baa755612cf4019b0 100644
--- a/content/common/gpu/media/vaapi_video_decode_accelerator.cc
+++ b/content/common/gpu/media/vaapi_video_decode_accelerator.cc
@@ -249,6 +249,7 @@ VaapiVideoDecodeAccelerator::VaapiVideoDecodeAccelerator(
       finish_flush_pending_(false),
       awaiting_va_surfaces_recycle_(false),
       requested_num_pics_(0),
+      min_picture_count_(0),
       bind_image_(bind_image),
       weak_this_factory_(this) {
   weak_this_ = weak_this_factory_.GetWeakPtr();
@@ -261,6 +262,7 @@ VaapiVideoDecodeAccelerator::~VaapiVideoDecodeAccelerator() {
 }
 
 bool VaapiVideoDecodeAccelerator::Initialize(media::VideoCodecProfile profile,
+                                             uint32 min_picture_count,
                                              Client* client) {
   DCHECK_EQ(message_loop_, base::MessageLoop::current());
 
@@ -308,6 +310,7 @@ bool VaapiVideoDecodeAccelerator::Initialize(media::VideoCodecProfile profile,
 
   CHECK(decoder_thread_.Start());
   decoder_thread_task_runner_ = decoder_thread_.task_runner();
+  min_picture_count_ = min_picture_count;
 
   state_ = kIdle;
   return true;
@@ -508,7 +511,9 @@ void VaapiVideoDecodeAccelerator::DecodeTask() {
         DVLOG(1) << "Decoder requesting a new set of surfaces";
         message_loop_->PostTask(FROM_HERE, base::Bind(
             &VaapiVideoDecodeAccelerator::InitiateSurfaceSetChange, weak_this_,
-                decoder_->GetRequiredNumOfPictures(),
+                std::max(min_picture_count_,
+                         static_cast<uint32_t>(
+                             decoder_->GetRequiredNumOfPictures())),
                 decoder_->GetPicSize()));
         // We'll get rescheduled once ProvidePictureBuffers() finishes.
         return;