Add "stylus-tools" Wayland protocol.

third_party/wayland-protocols/unstable/annotation/annotation-unstable-v1.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="annotation_unstable_v1">
+
+    <copyright>
+        Copyright 2017 The Chromium Authors.
+
+        Permission is hereby granted, free of charge, to any person obtaining a
+        copy of this software and associated documentation files (the "Software"),
+        to deal in the Software without restriction, including without limitation
+        the rights to use, copy, modify, merge, publish, distribute, sublicense,
+        and/or sell copies of the Software, and to permit persons to whom the
+        Software is furnished to do so, subject to the following conditions:
+
+        The above copyright notice and this permission notice (including the next
+        paragraph) shall be included in all copies or substantial portions of the
+        Software.
+
+        THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+        IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+        FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+        THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+        LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+        FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+        DEALINGS IN THE SOFTWARE.
+    </copyright>
+
+    <description summary="Protocol for the annotation layer">
+        This protocol specifies a set of interfaces to control the behavior
+        or the annotation layer, a special layer allowing the user to annotate
+        the on-screen content.
+
+        Warning! The protocol described in this file is experimental and backward
+        incompatible changes may be made. Backward compatible changes may be added
+        together with the corresponding interface version bump. Backward
+        incompatible changes are done by bumping the version number in the protocol
+        and interface names and resetting the interface version. Once the protocol
+        is to be declared stable, the 'z' prefix and the version number in the
+        protocol and interface names are removed and the interface version number is
+        reset.
+    </description>
+
+    <interface name="zcr_annotation_v1" version="1">
+        <description summary="annotation">
+            The global interface exposing the annotation layer capabilities is
+            used to instantiate an interface extension for a wl_surface object.
+            This extended interface will then allow the client to specify the
+            features of the annotation layer.
+        </description>
+
+        <request name="destroy" type="destructor">
+            <description summary="unbind from the annotation interface">
+                Informs the server that the client will not be using this
+                protocol object anymore. This does not affect any other objects,
+                annotation_features objects included.
+            </description>
+        </request>
+
+        <enum name="error">
+            <entry name="annotation_features_exists" value="0"
+                   summary="the surface already has an annotation_features object associated"/>
+        </enum>
+
+        <request name="get_annotation_features">
+            <description summary="extend surface interface for annotation_features">
+                Instantiate an interface extension for the given wl_surface to
+                provide access to the annotation layer features. If the given wl_surface
+                already has an annotation_features object associated, the
+                annotation_features_exists protocol error is raised.
+            </description>
+
+            <arg name="id" type="new_id" interface="zcr_annotation_features_v1"
+                 summary="the new annotation_features interface id"/>
+            <arg name="surface" type="object" interface="wl_surface"
+                 summary="the surface"/>
+        </request>
+    </interface>
+
+    <interface name="zcr_annotation_features_v1" version="1">

[reveman, 2017/05/23 16:41:06]

nit: please name this interface based on the functionality it provides instead
of this generic name. e.g. zcr_pointer_event_filter_v1.

[Vladislav Kaznacheev, 2017/05/23 23:48:56]

Done.

+        <description summary="annotation_features interface to a wl_surface">
+            An additional interface to a wl_surface object, which allows the
+            client to specify the features of the annotation layer.
+
+            If the wl_surface associated with the annotation_features object is destroyed,

[reveman, 2017/05/23 16:41:06]

nit: please break this line in a way that's consistent with l.80.

[Vladislav Kaznacheev, 2017/05/23 23:48:56]

Done.

+            the annotation_features object becomes inert.
+
+            If the annotation_features object is destroyed, the annotation_features state

[reveman, 2017/05/23 16:41:06]

nit: ditto

[Vladislav Kaznacheev, 2017/05/23 23:48:56]

Done.

+            is removed from the wl_surface. The change will be applied on the next
+            wl_surface.commit.
+        </description>
+
+        <request name="destroy" type="destructor">
+            <description summary="remove annotation_features from the surface">
+                The associated wl_surface's annotation_features state is removed.
+                The change is applied on the next wl_surface.commit.
+            </description>
+        </request>
+
+        <enum name="input_mode">

[reveman, 2017/05/23 16:41:06]

nit: avoid this enum and just use a boolean as there's only two values

[Vladislav Kaznacheev, 2017/05/23 23:48:56]

Done.

+            <description summary="mode">
+                Input mode: which types of input events should be handled by
+                the annotation layer.
+            </description>
+            <entry name="DEFAULT" value="0" summary="Handle all input events"/>
+            <entry name="STYLUS_ONLY" value="1" summary="Handle stylus only"/>
+        </enum>
+
+        <request name="set_input_mode">

[reveman, 2017/05/23 16:41:06]

nit: how about set_stylus_only(bool enabled)?

[Vladislav Kaznacheev, 2017/05/23 23:48:56]

Removed the parameter.

+            <description summary="set the input mode">
+                Set the input mode for the annotation layer associated with the
+                wl_surface.
+            </description>
+            <arg name="mode" type="uint" summary="the new input mode"/>
+        </request>
+
+    </interface>
+
+</protocol>