Add a ChromeOS implementation of VideoCaptureDevice

media/video/capture/linux/video_capture_device_linux.cc

Index: media/video/capture/linux/video_capture_device_linux.cc
diff --git a/media/video/capture/linux/video_capture_device_linux.cc b/media/video/capture/linux/video_capture_device_linux.cc
index 6893743d5110db0f634b58820b69718cf55a5a1d..0b1b28a09ce03d11b81f03846462a852afa9933f 100644
--- a/media/video/capture/linux/video_capture_device_linux.cc
+++ b/media/video/capture/linux/video_capture_device_linux.cc
@@ -22,6 +22,7 @@
 #include "base/files/scoped_file.h"
 #include "base/posix/eintr_wrapper.h"
 #include "base/strings/stringprintf.h"
+#include "ui/gfx/screen.h"
 
 namespace media {
 
@@ -271,9 +272,22 @@ VideoCaptureDeviceLinux::VideoCaptureDeviceLinux(const Name& device_name)
       v4l2_thread_("V4L2Thread"),
       buffer_pool_(NULL),
       buffer_pool_size_(0),
-      timeout_count_(0) {}
+      timeout_count_(0),
+      display_rotation_(gfx::Display::ROTATE_0) {
+  gfx::Screen* screen =

[perkj_chrome, 2014/05/09 10:11:28]

This will be called on a special thread used only for media devices? Is it ok to
run the display observer from any thread? 

+      gfx::Screen::GetScreenByType(gfx::SCREEN_TYPE_ALTERNATE);
+  if (screen) {
+    SetDisplayRotation(screen->GetPrimaryDisplay());
+    screen->AddObserver(this);
+  }
+}
 
 VideoCaptureDeviceLinux::~VideoCaptureDeviceLinux() {
+  gfx::Screen* screen =
+      gfx::Screen::GetScreenByType(gfx::SCREEN_TYPE_ALTERNATE);

[perkj_chrome, 2014/05/09 10:11:28]

Can there be a race here? ie, is it ok to not call RemoveObserver even if it was
added? 

+  if (screen)
+    screen->RemoveObserver(this);
+
   state_ = kIdle;
   // Check if the thread is running.
   // This means that the device have not been DeAllocated properly.
@@ -313,6 +327,27 @@ void VideoCaptureDeviceLinux::StopAndDeAllocate() {
   DeAllocateVideoBuffers();
 }
 
+void VideoCaptureDeviceLinux::OnDisplayBoundsChanged(
+    const gfx::Display& display) {
+  v4l2_thread_.message_loop()->PostTask(

[perkj_chrome, 2014/05/09 10:11:28]

This thread is started in AllocateAndStart. So you must verify that you are in
the correct state before posting. How about moving registration to
AllocateAndStart to ensure that this is safe. And deregister in the stop method.

[perkj_chrome, 2014/05/09 10:28:44]

oh- btw - this need a thread check to make sure its called on the same thread as
we do AllocateAndStart and Stop.... -- ie it must be called on the same thread
as we register and deregister the observer.

+      FROM_HERE,
+      base::Bind(&VideoCaptureDeviceLinux::SetDisplayRotation,
+                 base::Unretained(this), display));
+}
+
+void VideoCaptureDeviceLinux::OnDisplayAdded(
+    const gfx::Display& /*new_display*/) {}
+
+void VideoCaptureDeviceLinux::OnDisplayRemoved(
+    const gfx::Display& /*old_display*/) {}
+
+void VideoCaptureDeviceLinux::SetDisplayRotation(const gfx::Display& display) {
+  DCHECK(!v4l2_thread_.IsRunning() ||
+         v4l2_thread_.message_loop() == base::MessageLoop::current());
+  if (display.IsInternal())
+    display_rotation_ = display.rotation();

[perkj_chrome, 2014/05/09 10:18:52]

Add a todo and a comment that this will in fact rotate all cameras and why this
is done.

+}
+
 void VideoCaptureDeviceLinux::OnAllocateAndStart(int width,
                                                  int height,
                                                  int frame_rate,
@@ -521,7 +556,7 @@ void VideoCaptureDeviceLinux::OnCaptureTask() {
           static_cast<uint8*>(buffer_pool_[buffer.index].start),
           buffer.bytesused,
           capture_format_,
-          0,
+          display_rotation_ * 90,
           base::TimeTicks::Now());
 
       // Enqueue the buffer again.