Add support for multiple V4L2 video devices of the same type.

media/gpu/generic_v4l2_device.h

Index: media/gpu/generic_v4l2_device.h
diff --git a/media/gpu/generic_v4l2_device.h b/media/gpu/generic_v4l2_device.h
index 86d2df6699b2c236b9bee54d1a61102090c0bca9..846b5f8d40a77ef06b77013390d9f7a431929f6c 100644
--- a/media/gpu/generic_v4l2_device.h
+++ b/media/gpu/generic_v4l2_device.h
@@ -11,6 +11,8 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include <map>
+
 #include "base/files/scoped_file.h"
 #include "base/macros.h"
 #include "media/gpu/v4l2_device.h"
@@ -19,9 +21,10 @@ namespace media {
 
 class GenericV4L2Device : public V4L2Device {
  public:
-  explicit GenericV4L2Device(Type type);
+  GenericV4L2Device();
 
   // V4L2Device implementation.
+  bool Open(Type type, uint32_t v4l2_pixfmt) override;
   int Ioctl(int request, void* arg) override;
   bool Poll(bool poll_device, bool* event_pending) override;
   bool SetDevicePollInterrupt() override;
@@ -32,12 +35,11 @@ class GenericV4L2Device : public V4L2Device {
              int flags,
              unsigned int offset) override;
   void Munmap(void* addr, unsigned int len) override;
-  bool Initialize() override;
 
   std::vector<base::ScopedFD> GetDmabufsForV4L2Buffer(
       int index,
       size_t num_planes,
-      enum v4l2_buf_type type) override;
+      enum v4l2_buf_type buf_type) override;
 
   bool CanCreateEGLImageFrom(uint32_t v4l2_pixfmt) override;
   EGLImageKHR CreateEGLImage(
@@ -52,11 +54,54 @@ class GenericV4L2Device : public V4L2Device {
   EGLBoolean DestroyEGLImage(EGLDisplay egl_display,
                              EGLImageKHR egl_image) override;
   GLenum GetTextureTarget() override;
-  uint32_t PreferredInputFormat() override;
+  uint32_t PreferredInputFormat(Type type) override;
+
+  std::vector<uint32_t> GetSupportedImageProcessorPixelformats(
+      v4l2_buf_type buf_type) override;
+
+  VideoDecodeAccelerator::SupportedProfiles GetSupportedDecodeProfiles(
+      const size_t num_formats,
+      const uint32_t pixelformats[]) override;
+
+  VideoEncodeAccelerator::SupportedProfiles GetSupportedEncodeProfiles()
+      override;
+
+  bool IsImageProcessingSupported() override;
+
+  bool IsJpegDecodingSupported() override;
 
  private:
+  // Vector of video device node paths and corresponding pixelformats supported
+  // by each device node.
+  using Devices = std::vector<std::pair<std::string, std::vector<uint32_t>>>;
+
   ~GenericV4L2Device() override;
 
+  bool Initialize() override;
+
+  // Open device node for |path| as a device of |type|.
+  bool OpenDevicePath(const std::string& path, Type type);
+
+  // Close the currently open device.
+  void CloseDevice();
+
+  // Enumerate all V4L2 devices on the system for |type| and store the results
+  // under devices_by_type_[type].
+  void EnumerateDevicesForType(V4L2Device::Type type);
+
+  // Return device information for all devices of |type| available in the
+  // system. Enumerates and queries devices on first run and caches the results
+  // for subsequent calls.
+  const Devices& GetDevicesForType(V4L2Device::Type type);
+
+  // Return device node path for device of |type| supporting |pixfmt|, or
+  // an empty string if the given combination is not supported by the system.
+  std::string GetDevicePathFor(V4L2Device::Type type, uint32_t pixfmt);
+
+  // Stores information for all devices available on the system
+  // for each device Type.
+  std::map<V4L2Device::Type, Devices> devices_by_type_;
+
   // The actual device fd.
   base::ScopedFD device_fd_;