Add color metadata info to VideoDecoderConfig.

ui/gfx/color_space.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_COLOR_SPACE_H_
 #define UI_GFX_COLOR_SPACE_H_
 
 #include <stdint.h>
 
 #include "base/gtest_prod_util.h"
@@ skipping 52 matching lines @@
     LINEAR = 8,
     LOG = 9,
     LOG_SQRT = 10,
     IEC61966_2_4 = 11,
     BT1361_ECG = 12,
     IEC61966_2_1 = 13,
     BT2020_10 = 14,
     BT2020_12 = 15,
     SMPTEST2084 = 16,
     SMPTEST428_1 = 17,
+    ARIB_STD_B67 = 18,  // AKA hybrid-log gamma, HLG

[hubbe, 2016/09/15 17:25:52]

Also need to add this to ToLinear/FromLinear in color_transform.cc and
associated unit tests.

[servolk, 2016/09/15 20:29:04]

Done.
I've found some conversion formulas in Wikipedia
(https://en.wikipedia.org/wiki/Hybrid_Log-Gamma) and at
https://github.com/videovillage/Lattice-Issues/issues/52. Adding Steven to check
these are correct. IIUC we should use the formulas for the values normalized to
0..1 range here, right?
I think I might have done something wrong, since ColorSpaceTests start failing
when I add ARIB_STD_B67 into the all_transfers in color_transform_unittest.cc

PS: I've extracted the changes to add the new ARIB/HLG transfer function in a
separate CL so that it's easier to review and address gfx_unittest failures in
isolation from the rest of this CL:
https://codereview.chromium.org/2342963003/

[hubbe, 2016/09/15 20:46:12]

+1 for moving to a separate CL.
The 0-1 normalization is not clear. The specs that I followed for the other
transfer functions doesn't do that in all cases.

 
     // Chrome-specific values start at 1000.
     GAMMA24 = 1000,
 
     // This is an ad-hoc transfer function that decodes SMPTE 2084 content
     // into a 0-1 range more or less suitable for viewing on a non-hdr
     // display.
     SMPTEST2084_NON_HDR,
 
     // TODO(hubbe): Need to store an approximation of the gamma function(s).
@@ skipping 18 matching lines @@
 
     // Chrome-specific values start at 1000
     LAST = YDZDX,
   };
 
   // The h264 spec declares this as bool, so only the the first two values
   // correspond to the h264 spec. Chrome-specific values can start at 2.
   // We use an enum instead of a bool becuase different bit depths may have
   // different definitions of what "limited" means.
   enum class RangeID : int8_t {
-    FULL = 0,
+    UNSPECIFIED = 0,
     LIMITED = 1,
+    FULL = 2,
 
-    LAST = LIMITED
+    // Defined by TransferID/MatrixID
+    DERIVED = 3,
+
+    LAST = DERIVED
   };
 
   ColorSpace();
   ColorSpace(PrimaryID primaries,
              TransferID transfer,
              MatrixID matrix,
              RangeID full_range);
 
   static ColorSpace CreateSRGB();
   static ColorSpace CreateXYZD50();
@@ skipping 22 matching lines @@
 
   friend class ICCProfile;
   friend class ColorSpaceToColorSpaceTransform;
   friend struct IPC::ParamTraits<gfx::ColorSpace>;
   FRIEND_TEST_ALL_PREFIXES(SimpleColorSpace, GetColorSpace);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_COLOR_SPACE_H_