third_party: Add secure_output_protocol target to wayland-protocols.

third_party/wayland-protocols/src/unstable/secure-contents/secure-contents-unstable-v1.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="secure_contents_unstable_v1">
+
+  <copyright>
+    Copyright 2015 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 securing surface contents">

[Daniele Castagna, 2016/03/16 18:15:00]

nit: the other summaries seem to start with a lower case letter. But I see in
pointer-constraints they have the same inconsistency.

+    This protocol specifies a set of interfaces used to prevent surface
+    contents from appearing in screenshots or from being viewed on non-secure

[Daniele Castagna, 2016/03/16 18:15:00]

Maybe displayed instead of viewed? Also, non-secure output is not defined, but
we probably want to leave it that way.

+    outputs.
+
+    In order to secure surface contents, a client must first bind the global
+    interface "wp_secure_contents" which, if a compositor supports secure
+    contents, is exposed by the registry. Using the bound global object, the
+    client uses the "get_secure" request to instantiate an interface extension
+    for a wl_surface object. This extended interface will then allow surfaces
+    to be marked as having sensitive contents.
+
+    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="zwp_secure_contents_v1" version="1">
+    <description summary="secure contents">
+      The global interface exposing secure contents capabilities is used
+      to instantiate an interface extension for a wl_surface object.
+      This extended interface will then allow surfaces to be marked as
+      having sensitive contents, effectively preventing the surface from
+      from appearing in screenshots or from being viewed on non-secure
+      outputs.
+    </description>
+
+    <request name="destroy" type="destructor">
+      <description summary="unbind from the secure contents interface">
+        Informs the server that the client will not be using this

[Daniele Castagna, 2016/03/16 18:15:00]

Is the indentation correct?

+        protocol object anymore. This does not affect any other objects,
+        secure objects included.
+      </description>
+    </request>
+
+    <enum name="error">
+      <entry name="secure_exists" value="0"
+             summary="the surface already has a secure object associated"/>
+    </enum>
+
+    <request name="get_secure">
+      <description summary="extend surface interface for secure contents">
+        Instantiate an interface extension for the given wl_surface to

[Daniele Castagna, 2016/03/16 18:15:00]

Indentation?

+        provide securing of contents. If the given wl_surface already has
+        a secure object associated, the secure_exists protocol error
+        is raised.
+      </description>
+
+      <arg name="id" type="new_id" interface="zwp_secure_v1"
+           summary="the new secure interface id"/>
+      <arg name="surface" type="object" interface="wl_surface"
+           summary="the surface"/>
+    </request>
+  </interface>
+
+  <interface name="zwp_secure_v1" version="1">
+    <description summary="secure interface to a wl_surface">
+      An additional interface to a wl_surface object, which allows the
+      client to specify that a surface has sensitive surface contents.
+
+      If the wl_surface associated with the secure object is destroyed,
+      the secure object becomes inert.
+
+      If the secure object is destroyed, the sensitive contents
+      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 sensitive contents from the surface">
+        The associated wl_surface's senstaive contents state is removed.
+        The change is applied on the next wl_surface.commit.
+      </description>
+    </request>
+
+    <request name="enable_sensitive_contents">
+      <description summary="set the sensitive contents state">
+        Enable sensitive contents for wl_surface. See wp_secure_contents for
+        the description.
+
+        The sensitive contents state is double-buffered state, and will be
+        applied on the next wl_surface.commit.
+      </description>
+    </request>
+
+  </interface>
+</protocol>