Add flag to enable MJPEG acceleration for video capture

content/browser/renderer_host/gpu_jpeg_decoder.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 "content/browser/renderer_host/gpu_jpeg_decoder.h"
 
 #include "base/bind.h"
+#include "base/command_line.h"
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
 #include "base/trace_event/trace_event.h"
 #include "content/browser/gpu/browser_gpu_channel_host_factory.h"
 #include "content/common/gpu/client/gpu_jpeg_decode_accelerator_host.h"
 #include "content/public/browser/browser_thread.h"
+#include "content/public/common/content_switches.h"
 #include "media/base/video_frame.h"
 
 namespace content {
 
 // static
 bool GpuJpegDecoder::Supported() {
   // A lightweight check for caller to avoid IPC latency for known unsupported
   // platform. Initialize() can do the real platform supporting check but it
   // requires an IPC even for platforms that do not support HW decoder.
   // TODO(kcwu): move this information to GpuInfo.
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableAcceleratedMjpegDecode)) {
+#if defined(OS_CHROMEOS) && defined(ARCH_CPU_X86_FAMILY)

[piman, 2015/06/08 21:25:03]

nit: do you want to move the #ifdef around the switch test? That way you don't
pay for it on other platforms when it's always off.

[kcwu, 2015/06/09 09:05:13]

Done.

+    return true;
+#endif
+  }
   return false;
 }
 
 GpuJpegDecoder::GpuJpegDecoder(const DecodeDoneCB& decode_done_cb,
                                const ErrorCB& error_cb)
     : gpu_channel_event_(false /* manual reset */,
                          false /* initially_signaled */),
       decode_done_cb_(decode_done_cb),
       error_cb_(error_cb),
       next_bitstream_buffer_id_(0),
@@ skipping 154 matching lines @@
 
   {
     base::AutoLock lock(lock_);
     decode_done_closure_ = base::Bind(
         decode_done_cb_, base::Passed(&out_buffer), out_frame, timestamp);
   }
   decoder_->Decode(in_buffer_, out_frame);
 }
 
 }  // namespace content