Add VideoCaptureDevice::GetDeviceSupportedFormats to interface + implementation for Linux and Fake

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 6e685c381fd83527bb3c5dbe935191d3a61dac2c..00e3dc852edc7514306690558cddf3a2c5fc898f 100644
--- a/media/video/capture/linux/video_capture_device_linux.cc
+++ b/media/video/capture/linux/video_capture_device_linux.cc
@@ -96,7 +96,7 @@ static bool HasUsableFormats(int fd) {
                   fmtdesc.pixelformat) != usable_fourccs.end())
       return true;
 
-    fmtdesc.index++;
+    ++fmtdesc.index;
   }
   return false;
 }
@@ -252,6 +252,79 @@ const VideoCaptureDevice::Name& VideoCaptureDeviceLinux::device_name() {
   return device_name_;
 }
 
+void VideoCaptureDeviceLinux::GetDeviceSupportedFormats(
+    const std::string& device_name,
+    VideoCaptureFormats* capture_formats) {
+
+  int fd = open(device_name.c_str(), O_RDONLY);
+  if (fd < 0)
+    return;
+
+  media::VideoCaptureCapability capture_format;
+
+  v4l2_capability device;
+  // Test if this is a V4L2 capture device.
+  if ((ioctl(fd, VIDIOC_QUERYCAP, &device) == 0) &&
+      (device.capabilities & V4L2_CAP_VIDEO_CAPTURE) &&
+      !(device.capabilities & V4L2_CAP_VIDEO_OUTPUT)) {
+    // Retrieve the caps one by one, first get colorspace, then sizes, then
+    // framerates. See http://linuxtv.org/downloads/v4l-dvb-apis for reference.
+    v4l2_fmtdesc pixel_format = {};
+    pixel_format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    while (ioctl(fd, VIDIOC_ENUM_FMT, &pixel_format) == 0) {
+      capture_format.color = media::V4l2ColorToVideoCaptureColorFormat(
+          static_cast<int32>(pixel_format.pixelformat));
+
+      v4l2_frmsizeenum frame_size = {};
+      frame_size.pixel_format = pixel_format.pixelformat;
+      while (ioctl(fd, VIDIOC_ENUM_FRAMESIZES, &frame_size) == 0) {
+        if (frame_size.type == V4L2_FRMSIZE_TYPE_DISCRETE) {
+          capture_format.width = frame_size.discrete.width;
+          capture_format.height = frame_size.discrete.height;
+        } else if (frame_size.type == V4L2_FRMSIZE_TYPE_STEPWISE) {
+          // What to do here? We get a min-max pair for width and height, and a
+          // step for each dimensions. Is not a crazy format, ViVi uses it.
+          // TODO(mcasas) see crbug.com/249953
+          NOTIMPLEMENTED();
+        } else if (frame_size.type == V4L2_FRMSIZE_TYPE_CONTINUOUS) {
+          // Same here as the case before: TODO(mcasas) see crbug.com/249953
+          NOTIMPLEMENTED();
+        }
+        v4l2_frmivalenum frame_interval = {};
+        frame_interval.pixel_format = pixel_format.pixelformat;
+        frame_interval.width = frame_size.discrete.width;
+        frame_interval.height = frame_size.discrete.height;
+        while (ioctl(fd, VIDIOC_ENUM_FRAMEINTERVALS, &frame_interval) == 0) {
+          if (frame_interval.type == V4L2_FRMIVAL_TYPE_DISCRETE) {
+            capture_format.frame_rate =
+                (frame_interval.discrete.numerator != 0)
+                    ? (static_cast<float>(frame_interval.discrete.denominator) /
+                       static_cast<float>(frame_interval.discrete.numerator))
+                    : 0;
+
+          } else if (frame_interval.type == V4L2_FRMIVAL_TYPE_CONTINUOUS) {
+            // Same here as the case above: TODO(mcasas) see crbug.com/249953
+            NOTIMPLEMENTED();
+            break;
+          } else if (frame_interval.type == V4L2_FRMIVAL_TYPE_STEPWISE) {
+            // Same here as the case before: TODO(mcasas) see crbug.com/249953
+            NOTIMPLEMENTED();
+            break;
+          }
+          capture_formats->insert(capture_formats->end(), capture_format);
+          ++frame_interval.index;
+        }
+        ++frame_size.index;
+      }
+      ++pixel_format.index;
+    }
+  } else {
+    // The selected device is not video capture as we like it.
+    capture_formats->clear();
+  }
+  close(fd);
+}
+
 void VideoCaptureDeviceLinux::OnAllocate(int width,
                                          int height,
                                          int frame_rate,
@@ -292,7 +365,7 @@ void VideoCaptureDeviceLinux::OnAllocate(int width,
   std::list<int>::iterator best = v4l2_formats.end();
   while (ioctl(device_fd_, VIDIOC_ENUM_FMT, &fmtdesc) == 0) {
     best = std::find(v4l2_formats.begin(), best, fmtdesc.pixelformat);
-    fmtdesc.index++;
+    ++fmtdesc.index;
   }
 
   if (best == v4l2_formats.end()) {
@@ -449,7 +522,7 @@ void VideoCaptureDeviceLinux::OnCaptureTask() {
 
   // Check if select timeout.
   if (result == 0) {
-    timeout_count_++;
+    ++timeout_count_;
     if (timeout_count_ >= kContinuousTimeoutLimit) {
       SetErrorState(base::StringPrintf(
           "Continuous timeout %d times", timeout_count_));
@@ -510,7 +583,7 @@ bool VideoCaptureDeviceLinux::AllocateVideoBuffers() {
 
   // Map the buffers.
   buffer_pool_ = new Buffer[r_buffer.count];
-  for (unsigned int i = 0; i < r_buffer.count; i++) {
+  for (unsigned int i = 0; i < r_buffer.count; ++i) {
     v4l2_buffer buffer;
     memset(&buffer, 0, sizeof(buffer));
     buffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
@@ -542,7 +615,7 @@ void VideoCaptureDeviceLinux::DeAllocateVideoBuffers() {
     return;
 
   // Unmaps buffers.
-  for (int i = 0; i < buffer_pool_size_; i++) {
+  for (int i = 0; i < buffer_pool_size_; ++i) {
     munmap(buffer_pool_[i].start, buffer_pool_[i].length);
   }
   v4l2_requestbuffers r_buffer;