Add "stylus-tools" Wayland protocol.

third_party/wayland-protocols/unstable/stylus-tools/stylus-tools-unstable-v1.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="stylus_tools_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 stylus tools">
+    This protocol specifies a set of interfaces used to control the behavior
+    of stylus tools.
+
+    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_stylus_tools_v1" version="1">
+    <description summary="stylus_tools">
+      The global interface is used to instantiate an interface extension for a
+      wl_surface object. This extended interface will then allow the client to
+      control the stylus-related behavior of the window associated with the

[reveman, 2017/05/24 13:38:57]

nit: "window associated with..." there's no concept of anything called a window
in the wayland world so this is leaking some implementation details into the
protocol. please reword. maybe " control the stylus-related behavior for input
device event processing related to wl_surface."?

[Vladislav Kaznacheev, 2017/05/24 18:11:14]

Done.

+      wl_surface.
+    </description>
+
+    <request name="destroy" type="destructor">
+      <description summary="unbind from the stylus_tools interface">
+        Informs the server that the client will not be using this
+        protocol object anymore. This does not affect any other objects,
+        stylus_tool objects included.
+      </description>
+    </request>
+
+    <enum name="error">
+      <entry name="stylus_tool_exists" value="0"
+        summary="the surface already has a stylus_tool object associated"/>
+    </enum>
+
+    <request name="get_stylus_tool">
+      <description summary="extend surface interface for stylus_tool">
+        Instantiate an interface extension for the given wl_surface to
+        provide access to the stylus tools features. If the given
+        wl_surface already has an stylus_tool object associated,
+        the stylus_tool_exists protocol protocol error is raised.
+      </description>
+
+      <arg name="id" type="new_id" interface="zcr_stylus_tool_v1"
+        summary="the new stylus_tool interface id"/>
+      <arg name="surface" type="object" interface="wl_surface"
+        summary="the surface"/>
+    </request>
+  </interface>
+
+  <interface name="zcr_stylus_tool_v1" version="1">
+    <description summary="stylus_tool interface to a wl_surface">
+      An additional interface to a wl_surface object, which allows the
+      client to control the behavior of stylus tools.
+
+      If the wl_surface associated with the stylus_tool object is destroyed,
+      the stylus_tool object becomes inert.
+
+      If the stylus_tool object is destroyed, the stylus_tool state 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 stylus_tool from the surface">
+        The associated wl_surface's stylus_tool state is removed.
+        The change is applied on the next wl_surface.commit.
+      </description>
+    </request>
+
+    <request name="set_stylus_only">
+      <description summary="Set the stylus-only mode">
+        Enables the "stylus-only" mode for the window associated with the

[reveman, 2017/05/24 13:38:57]

nit: ditto. remove the term "window" somehow and just refer to input events

[Vladislav Kaznacheev, 2017/05/24 18:11:14]

Done.

+        wl_surface.
+      </description>
+    </request>
+  </interface>
+
+</protocol>