MJPEG acceleration for video capture using VAAPI

content/common/gpu/client/gpu_channel_host.cc

Index: content/common/gpu/client/gpu_channel_host.cc
diff --git a/content/common/gpu/client/gpu_channel_host.cc b/content/common/gpu/client/gpu_channel_host.cc
index aa47e2fd677bad9d115abb27209433292689fe57..e8808fe8a91fe9ae3457a8ae8eb5a331755d6689 100644
--- a/content/common/gpu/client/gpu_channel_host.cc
+++ b/content/common/gpu/client/gpu_channel_host.cc
@@ -13,6 +13,7 @@
 #include "base/threading/thread_restrictions.h"
 #include "base/trace_event/trace_event.h"
 #include "content/common/gpu/client/command_buffer_proxy_impl.h"
+#include "content/common/gpu/client/gpu_jpeg_decode_accelerator_host.h"
 #include "content/common/gpu/gpu_messages.h"
 #include "ipc/ipc_sync_message_filter.h"
 #include "url/gurl.h"
@@ -256,6 +257,28 @@ scoped_ptr<media::VideoEncodeAccelerator> GpuChannelHost::CreateVideoEncoder(
   return it->second->CreateVideoEncoder();
 }
 
+scoped_ptr<media::JpegDecodeAccelerator> GpuChannelHost::CreateJpegDecoder(
+    scoped_refptr<base::MessageLoopProxy> reply_loop) {
+  TRACE_EVENT0("gpu", "GpuChannelHost::CreateJpegDecoder");
+  // This function is called from GpuJpegDecoder's main task thread, which is

[wuchengli, 2015/04/24 05:54:23]

Just call it task thread. main task thread sounds confusing.

[kcwu, 2015/04/30 19:25:40]

Done.

+  // not main thread.
+
+  int32 route_id = GenerateRouteID();
+  GpuJpegDecodeAcceleratorHost* decoder(
+      new GpuJpegDecodeAcceleratorHost(this, route_id,
+                                       factory_->GetIOLoopProxy()));
+
+  // GpuJpegDecoder's main task thread (i.e., device thread on Linux) is
+  // usually blocking wait for next frame, so it expects decoder responses are

[wuchengli, 2015/04/24 05:54:23]

s/blocking wait/waiting/.

Here it refers to the main task thread, which doesn't expect anything. I think
this is clearer. s/it expects decoder responses are send/decoder responses are
sent/. 

[kcwu, 2015/04/30 19:25:40]

Done.

+  // send to |reply_loop| directly.
+  scoped_refptr<base::MessageLoopProxy> io_loop = factory_->GetIOLoopProxy();
+  io_loop->PostTask(FROM_HERE,
+                    base::Bind(&GpuChannelHost::MessageFilter::AddRoute,
+                               channel_filter_.get(), route_id,
+                               decoder->AsWeakPtr(), reply_loop));

[wuchengli, 2015/04/24 05:54:23]

Why not just use |io_loop|? reply_loop is always IO thread.
GpuJpegDecoder::Initialize also hard-codes the IO thread there. DCHECK in
VideoFrameReady should make sure it's the right thread.

[kcwu, 2015/04/30 19:25:40]

I want to make these thread logic stay in GpuJpegDecoder as much as possible.
Make GpuChannelHost neutral.

+  return scoped_ptr<media::JpegDecodeAccelerator>(decoder);
+}
+
 void GpuChannelHost::DestroyCommandBuffer(
     CommandBufferProxyImpl* command_buffer) {
   TRACE_EVENT0("gpu", "GpuChannelHost::DestroyCommandBuffer");