Introduce GpuVideoDecodeAcceleratorFactory.

content/public/gpu/BUILD.gn

 # Copyright 2016 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.
 
 # See //content/BUILD.gn for how this works.
 group("gpu") {
   if (is_component_build) {
     public_deps = [
       "//content",
     ]
   } else {
     public_deps = [
       ":gpu_sources",
     ]
   }
 }
 
 source_set("gpu_sources") {
   visibility = [ "//content/*" ]
 
   sources = [
     "content_gpu_client.h",
+    "gpu_video_decode_accelerator_factory.cc",
+    "gpu_video_decode_accelerator_factory.h",
   ]
 
   deps = [
     "//base",
     "//content:export",
     "//content/gpu:gpu_sources",
     "//content/public/common:common_sources",
+    "//gpu/command_buffer/service:service_sources",
+    "//gpu/config:config_sources",

[boliu, 2016/03/25 17:49:08]

The problem was gpu/command_buffer/service and gpu/config are being built twice
in gn component build. Once into the content shared lib, and once into the gpu
shared lib.

I think these should not have been deps on the source of the targets, but the
targets themselves? Fix here: https://codereview.chromium.org/1838493002

+    "//media:media",
   ]
 
   allow_circular_includes_from = [ "//content/gpu:gpu_sources" ]
 }