PPAPI: Make output protection API work with mus+ash

services/ui/public/interfaces/display/output_protection.mojom

Index: services/ui/public/interfaces/display/output_protection.mojom
diff --git a/services/ui/public/interfaces/display/output_protection.mojom b/services/ui/public/interfaces/display/output_protection.mojom
new file mode 100644
index 0000000000000000000000000000000000000000..f021be779317040f1ad0595273b22bf0f26f6468
--- /dev/null
+++ b/services/ui/public/interfaces/display/output_protection.mojom
@@ -0,0 +1,21 @@
+// Copyright 2017 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.
+
+module display.mojom;
+
+// An interface for clients that are allowed to control the display output
+// content protection.
+interface OutputProtection {

[sky, 2017/02/10 19:24:56]

Do we care about multiple clients trying to use this interface at once? Should
only one client be allowed to use it at a time?

[Peng, 2017/02/10 20:35:47]

I am not sure. But I checked the netflix, it will call
QueryContentProtectionStatus() repeatedly to make sure the current display is
protected. If the display is not protected, I think netflix will call
EnableContentProtection() again to enable the protection or stop playing.

kcwu@, Could you please give us more detail? Thanks

[kcwu, 2017/02/11 01:45:21]

The api allows multiple clients at the same time. The implementation should
enable protection if at least one client request protection.
The protection may be disabled due to connection changed or other reasons, so
the client will query status to make sure the protection is correctly enabled.

[Peng, 2017/02/13 21:14:46]

Refined the document.

+  // Queries link status and protection status.
+  QueryContentProtectionStatus(int64 display_id) => (bool success,
+                                                     uint32 link_mask,
+                                                     uint32 protection_mask);
+
+  // Requests the desired protection methods.
+  // |protection_mask| is the desired protection methods, which is a bitmask
+  // of the ContentProtectionMethod values.
+  // Returns true when the protection request has been made.
+  EnableContentProtection(int64 display_id,

[sky, 2017/02/10 19:24:56]

Isn't this more of SetContentProtectionMethod() ?

Also, I assume the content protection reverts to non when the interface is
closed. If not it should, please document that.

[Peng, 2017/02/10 20:35:47]

I assume it too.

kcwu@, Could you please confirm it?

[kcwu, 2017/02/11 01:45:21]

Yes. When the interface is closed, the request from the said client will be
removed. But the protection maybe still be enabled if there are still other
clients requesting protection.
About naming, I agree now, "set" seems better than "enable". I forgot why I
named it "enable" at that time.

[Peng, 2017/02/13 21:14:46]

Refined the document. And renamed it to SetContentProtection.

+                          uint32 desired_method_mask) => (bool success);

[sky, 2017/02/10 19:24:56]

Please define the enum in the mojom.

[Peng, 2017/02/10 20:35:47]

For the desired_method_mask? But chrome doesn't use enum for it, chrome just
uses uint32_t.
And the ContentProtectionMethod[1] is never used as function args type.

[1]
https://cs.chromium.org/chromium/src/ui/display/types/display_constants.h?typ...

[kcwu, 2017/02/11 01:45:21]

It is a bitmask in order to support other protection mechanism. However, so far
we only support HDCP.

+};