File Video Capture: allow IO operations from Device thread

media/capture/video/file_video_capture_device_factory.cc

 // Copyright 2014 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 "media/capture/video/file_video_capture_device_factory.h"
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/strings/sys_string_conversions.h"
+#include "base/threading/thread_restrictions.h"
 #include "build/build_config.h"
 #include "media/base/media_switches.h"
 #include "media/capture/video/file_video_capture_device.h"
 
 namespace media {
 
 const char kFileVideoCaptureDeviceName[] =
     "/dev/placeholder-for-file-backed-fake-capture-device";
 
 // Inspects the command line and retrieves the file path parameter.
 base::FilePath GetFilePathFromCommandLine() {
   base::FilePath command_line_file_path =
       base::CommandLine::ForCurrentProcess()->GetSwitchValuePath(
           switches::kUseFileForFakeVideoCapture);
   CHECK(!command_line_file_path.empty());
   return command_line_file_path;
 }
 
 std::unique_ptr<VideoCaptureDevice> FileVideoCaptureDeviceFactory::CreateDevice(
     const VideoCaptureDeviceDescriptor& device_descriptor) {
   DCHECK(thread_checker_.CalledOnValidThread());
+  base::ThreadRestrictions::AssertIOAllowed();
 #if defined(OS_WIN)
   return std::unique_ptr<VideoCaptureDevice>(new FileVideoCaptureDevice(
       base::FilePath(base::SysUTF8ToWide(device_descriptor.display_name))));
 #else
   return std::unique_ptr<VideoCaptureDevice>(new FileVideoCaptureDevice(
       base::FilePath(device_descriptor.display_name)));
 #endif
 }
 
 void FileVideoCaptureDeviceFactory::GetDeviceDescriptors(
     VideoCaptureDeviceDescriptors* device_descriptors) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(device_descriptors->empty());
+  base::ThreadRestrictions::SetIOAllowed(true);
+
   const base::FilePath command_line_file_path = GetFilePathFromCommandLine();
   device_descriptors->emplace_back(
 #if defined(OS_WIN)
       base::SysWideToUTF8(command_line_file_path.value()),
       kFileVideoCaptureDeviceName, VideoCaptureApi::WIN_DIRECT_SHOW
 #elif defined(OS_MACOSX)
       command_line_file_path.value(), kFileVideoCaptureDeviceName,
       VideoCaptureApi::MACOSX_AVFOUNDATION
 #elif defined(OS_LINUX)
       command_line_file_path.value(), kFileVideoCaptureDeviceName,
       VideoCaptureApi::LINUX_V4L2_SINGLE_PLANE
 #else
       command_line_file_path.value(), kFileVideoCaptureDeviceName,
       VideoCaptureApi::UNKNOWN
 #endif
       );
 }
 
 void FileVideoCaptureDeviceFactory::GetSupportedFormats(
     const VideoCaptureDeviceDescriptor& device_descriptor,
     VideoCaptureFormats* supported_formats) {
   DCHECK(thread_checker_.CalledOnValidThread());
+  base::ThreadRestrictions::AssertIOAllowed();
 
   VideoCaptureFormat capture_format;
   if (!FileVideoCaptureDevice::GetVideoCaptureFormat(
         GetFilePathFromCommandLine(), &capture_format)) {
     return;
   }
 
   supported_formats->push_back(capture_format);
 }
 
 }  // namespace media