Do not use libv4l if no plugin is registered.

content/common/gpu/media/generic_v4l2_device.cc

Index: content/common/gpu/media/generic_v4l2_device.cc
diff --git a/content/common/gpu/media/generic_v4l2_device.cc b/content/common/gpu/media/generic_v4l2_device.cc
index 67600487cae722cb93d2d16d9dad8e976d3ed5a7..24b92ecd89b7510be02241c56a62b7a1790da27b 100644
--- a/content/common/gpu/media/generic_v4l2_device.cc
+++ b/content/common/gpu/media/generic_v4l2_device.cc
@@ -29,9 +29,6 @@ using content_common_gpu_media::StubPathMap;
 
 static const base::FilePath::CharType kV4l2Lib[] =
     FILE_PATH_LITERAL("/usr/lib/libv4l2.so");
-#else
-#define v4l2_close close
-#define v4l2_ioctl ioctl
 #endif
 
 namespace content {
@@ -45,7 +42,8 @@ const char kImageProcessorDevice[] = "/dev/gsc0";
 GenericV4L2Device::GenericV4L2Device(Type type)
     : type_(type),
       device_fd_(-1),
-      device_poll_interrupt_fd_(-1) {}
+      device_poll_interrupt_fd_(-1),
+      use_libv4l2_(false) {}
 
 GenericV4L2Device::~GenericV4L2Device() {
   if (device_poll_interrupt_fd_ != -1) {
@@ -53,13 +51,27 @@ GenericV4L2Device::~GenericV4L2Device() {
     device_poll_interrupt_fd_ = -1;
   }
   if (device_fd_ != -1) {
-    v4l2_close(device_fd_);
+    Close();
     device_fd_ = -1;
   }
 }
 
+void GenericV4L2Device::Close() {
+#if defined(USE_LIBV4L2)
+  if (use_libv4l2_) {
+    v4l2_close(device_fd_);
+    return;
+  }
+#endif
+  close(device_fd_);

[Pawel Osciak, 2015/04/21 05:02:42]

Perhaps this would be a good time to start using base::ScopedFd for both fds?

[wuchengli, 2015/04/21 06:12:10]

Good idea. Done.

+}
+
 int GenericV4L2Device::Ioctl(int request, void* arg) {
-  return HANDLE_EINTR(v4l2_ioctl(device_fd_, request, arg));
+#if defined(USE_LIBV4L2)
+  if (use_libv4l2_)
+    return HANDLE_EINTR(v4l2_ioctl(device_fd_, request, arg));
+#endif
+  return HANDLE_EINTR(ioctl(device_fd_, request, arg));
 }
 
 bool GenericV4L2Device::Poll(bool poll_device, bool* event_pending) {
@@ -153,9 +165,9 @@ bool GenericV4L2Device::Initialize() {
     return false;
   }
 #if defined(USE_LIBV4L2)
-  if (HANDLE_EINTR(v4l2_fd_open(device_fd_, V4L2_DISABLE_CONVERSION)) == -1) {
-    v4l2_close(device_fd_);
-    return false;
+  if (HANDLE_EINTR(v4l2_fd_open(device_fd_, V4L2_DISABLE_CONVERSION)) >= 0) {

[Pawel Osciak, 2015/04/21 05:02:42]

I'd prefer != -1.

[wuchengli, 2015/04/21 06:12:10]

Done. I was confused when I discussed with you. != -1 is correct.

+    DVLOG(2) << "Found a libv4l2 plugin for " << device_path;

[Pawel Osciak, 2015/04/21 05:02:42]

v4l2_fd_open succeeding is not exactly equivalent of finding a plugin. I know
right now it is, but I'd prefer not calling this out explicitly. Could we
instead say "using libvl42 for " or something like that?

[wuchengli, 2015/04/21 06:12:10]

Done.

+    use_libv4l2_ = true;
   }
 #endif