First cut at making HDR content viewable on SDR display with color management.

ui/gfx/color_space.h

Index: ui/gfx/color_space.h
diff --git a/ui/gfx/color_space.h b/ui/gfx/color_space.h
index 247e641d7825d6fce38cddee4ad5e5baf91c4e4d..b7b93786a55309b9e54596ab68498093c01a4d19 100644
--- a/ui/gfx/color_space.h
+++ b/ui/gfx/color_space.h
@@ -74,8 +74,13 @@ class GFX_EXPORT ColorSpace {
     // 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).
-    CUSTOM = 1001,
+    CUSTOM,
     LAST = CUSTOM,
   };