Reland: Video Capture: extract storage info from pixel format in VideoCaptureFormat.

media/base/video_capture_types.h

Index: media/base/video_capture_types.h
diff --git a/media/base/video_capture_types.h b/media/base/video_capture_types.h
index 520dafda38d7e99b7bf9f30e8d4edce22badfcd2..1d85aa0cb0a2d031d75cfc60445b6a7cd1e5cbdb 100644
--- a/media/base/video_capture_types.h
+++ b/media/base/video_capture_types.h
@@ -18,6 +18,7 @@ namespace media {
 typedef int VideoCaptureSessionId;
 
 // Color formats from camera. This list is sorted in order of preference.
+// TODO(mcasas): Consider if this list can be merged with media::Format.
 enum VideoPixelFormat {
   PIXEL_FORMAT_I420,
   PIXEL_FORMAT_YV12,
@@ -29,12 +30,19 @@ enum VideoPixelFormat {
   PIXEL_FORMAT_RGB32,
   PIXEL_FORMAT_ARGB,
   PIXEL_FORMAT_MJPEG,
-  PIXEL_FORMAT_TEXTURE,  // Capture format as a GL texture.
-  PIXEL_FORMAT_GPUMEMORYBUFFER,
   PIXEL_FORMAT_UNKNOWN,  // Color format not set.
   PIXEL_FORMAT_MAX,
 };
 
+// Storage type for the pixels. In principle, all combinations of Storage and
+// Format are possible, though some are very typical, such as texture + ARGB,
+// and others are only available if the platform allows it e.g. GpuMemoryBuffer.
+enum VideoPixelStorage {

[mcasas, 2015/06/24 21:23:23]

dcheng@ enum class.

I don't understand, do you mean I should make a class to wrap 
this enum? It's not customary in media/, I'd be happy to follow
up in another CL if this is interesting.

[dcheng, 2015/06/24 21:41:47]

enum class VideoPixelStorage {
  CPU,
  TEXTURE,
  GPUMEMORYBUFFER,
};

(Incidentally, what does CPU mean anyway? I assume that means it's in main
memory?)

[mcasas, 2015/06/25 01:19:51]

I wrote a bug to do this in the near future, together with 
a similar change for VideoPixelFormat. The reason for not
doing it on the spot is that DCHECK_EQ has troubles to
print out enum classes when the condition does not verify,
and the changes would be too widespread for this CL.
Yes, it means precisely that.

[dcheng, 2015/06/25 02:02:18]

Some comments here would be nice =)

+  PIXEL_STORAGE_CPU,
+  PIXEL_STORAGE_TEXTURE,
+  PIXEL_STORAGE_GPUMEMORYBUFFER,
+};
+
 // Policies for capture devices that have source content that varies in size.
 // It is up to the implementation how the captured content will be transformed
 // (e.g., scaling and/or letterboxing) in order to produce video frames that
@@ -71,9 +79,15 @@ struct MEDIA_EXPORT VideoCaptureFormat {
   VideoCaptureFormat(const gfx::Size& frame_size,
                      float frame_rate,
                      VideoPixelFormat pixel_format);
+  VideoCaptureFormat(const gfx::Size& frame_size,
+                     float frame_rate,
+                     VideoPixelFormat pixel_format,
+                     VideoPixelStorage pixel_storage);
 
+  // TODO(mcasas): Remove this method http://crbug.com/501134.
   std::string ToString() const;
   static std::string PixelFormatToString(VideoPixelFormat format);
+  static std::string PixelStorageToString(VideoPixelStorage storage);
 
   // Returns the required buffer size to hold an image of a given
   // VideoCaptureFormat with no padding and tightly packed.
@@ -92,6 +106,7 @@ struct MEDIA_EXPORT VideoCaptureFormat {
   gfx::Size frame_size;
   float frame_rate;
   VideoPixelFormat pixel_format;
+  VideoPixelStorage pixel_storage;
 };
 
 typedef std::vector<VideoCaptureFormat> VideoCaptureFormats;