Implement canvas color space IDL format for 2D canvas

third_party/WebKit/Source/core/html/canvas/CanvasContextCreationAttributes.idl

 // Copyright 2014 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.
 
 // The spec for HTMLCanvasElement.getContext() defines the context
 // creation attributes as type "any". In order to eliminate custom
 // bindings for getContext(), we define a dictionary that contains the
 // union of all of the context types' attributes. Note that it is not
 // possible to use a union type for this purpose because two dictionary
 // types are not distinguishable.
 //
 // Fortunately, there aren't any context creation attributes which are
 // defined with different default values in different context
 // specifications. (The "alpha" value, in particular, has a default
 // value of true for both the Canvas2D and WebGL specifications.)
 //
 // The PermissiveDictionaryConversion extended attribute ignores
 // non-object types (like 'true' and 'false') passed to getContext() for
 // the attributes instead of raising TypeError, following the behavior
 // of the previous custom binding.
 //
 // N.B.: Web IDL doesn't support multiple inheritance of dictionaries.
 
+enum CanvasColorSpace {
+    "srgb", // default
+    "rec2020",
+    "p3",
+};
 
-enum CanvasColorSpace { "legacy-srgb", "srgb", "linear-rgb", "rec-2020", "p3"};
+enum CanvasPixelFormat {
+    "8-8-8-8", // default
+    "10-10-10-2",
+    "12-12-12-12",
+    "float16",
+};
 
 [PermissiveDictionaryConversion]
 dictionary CanvasContextCreationAttributes {
     // Canvas 2D attributes
     boolean alpha = true;  // Also used for WebGL.
+    // TODO(crbug.com/637288): Do we keep "legacy-srgb" as the default?
+    // Must decide before shipping.
     [RuntimeEnabled=ExperimentalCanvasFeatures] CanvasColorSpace colorSpace = "legacy-srgb";
+    [RuntimeEnabled=ExperimentalCanvasFeatures] CanvasPixelFormat pixelFormat = "8-8-8-8";
+    [RuntimeEnabled=ExperimentalCanvasFeatures] boolean linearPixelMath = false;
 
     // WebGL attributes
     boolean depth = true;
     boolean stencil = false;
     boolean antialias = true;
     boolean premultipliedAlpha = true;
     boolean preserveDrawingBuffer = false;
     boolean failIfMajorPerformanceCaveat = false;
 };