Implement navigator.requestMediaKeySystemAccess()

Source/modules/encryptedmedia/MediaKeySystemAccess.cpp

+// 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.
+
+#include "config.h"
+#include "modules/encryptedmedia/MediaKeySystemAccess.h"
+
+#include "bindings/core/v8/ScriptPromiseResolver.h"
+#include "bindings/core/v8/ScriptState.h"
+#include "core/dom/DOMException.h"
+#include "core/dom/Document.h"
+#include "core/dom/ExceptionCode.h"
+#include "modules/encryptedmedia/MediaKeys.h"
+#include "modules/encryptedmedia/MediaKeysController.h"
+#include "platform/Logging.h"
+#include "platform/Timer.h"
+#include "public/platform/WebContentDecryptionModule.h"
+
+namespace blink {
+
+// This class allows a MediaKeys object to be created asynchronously.
+class MediaKeysInitializer : public ScriptPromiseResolver {
+    WTF_MAKE_NONCOPYABLE(MediaKeysInitializer);
+
+public:
+    static ScriptPromise create(ScriptState*, const String& keySystem);
+    virtual ~MediaKeysInitializer();
+
+private:
+    MediaKeysInitializer(ScriptState*, const String& keySystem);
+    void timerFired(Timer<MediaKeysInitializer>*);
+
+    const String m_keySystem;
+    Timer<MediaKeysInitializer> m_timer;
+};
+
+ScriptPromise MediaKeysInitializer::create(ScriptState* scriptState, const String& keySystem)
+{
+    RefPtr<MediaKeysInitializer> initializer = adoptRef(new MediaKeysInitializer(scriptState, keySystem));
+    initializer->suspendIfNeeded();
+    initializer->keepAliveWhilePending();
+    return initializer->promise();
+}
+
+MediaKeysInitializer::MediaKeysInitializer(ScriptState* scriptState, const String& keySystem)
+    : ScriptPromiseResolver(scriptState)
+    , m_keySystem(keySystem)
+    , m_timer(this, &MediaKeysInitializer::timerFired)
+{
+    WTF_LOG(Media, "MediaKeysInitializer::MediaKeysInitializer");
+    // Start the timer so that MediaKeys can be created asynchronously.
+    m_timer.startOneShot(0, FROM_HERE);
+}
+
+MediaKeysInitializer::~MediaKeysInitializer()
+{
+    WTF_LOG(Media, "MediaKeysInitializer::~MediaKeysInitializer");
+}
+
+void MediaKeysInitializer::timerFired(Timer<MediaKeysInitializer>*)
+{
+    WTF_LOG(Media, "MediaKeysInitializer::timerFired");
+
+    // NOTE: Continued from step 2. of MediaKeySystemAccess::createMediaKeys().
+    // 2.1 Let cdm be the CDM corresponding to this object.
+    // 2.2 Load and initialize the cdm if necessary.
+    Document* document = toDocument(executionContext());

[ddorwin, 2014/10/22 22:18:54]

OOC, should we be saving the execution context in the synchronous part?

[jrummell, 2014/10/23 01:20:02]

The execution context is part of ScriptState.

+    MediaKeysController* controller = MediaKeysController::from(document->page());
+    OwnPtr<WebContentDecryptionModule> cdm = controller->createContentDecryptionModule(executionContext(), m_keySystem);

[ddorwin, 2014/10/22 22:18:54]

Maybe we should modify the creation function to return a cause so we can provide
something other than UnknownError.

[jrummell, 2014/10/23 01:20:03]

Added FIXME. Also should it be async?

+
+    // 2.3 If cdm fails to load or initialize, reject promise with a new
+    //     DOMException whose name is the appropriate error name.
+    if (!cdm) {
+        String message("A content decryption module could not be loaded for the '" + m_keySystem + "' key system.");

[ddorwin, 2014/10/22 22:18:54]

I think it's more accurate to say "A CDM instance could not be created for..."

[jrummell, 2014/10/23 01:20:02]

Done.

+        reject(DOMException::create(UnknownError, message));
+        return;
+    }
+
+    // 2.4 Let media keys be a new MediaKeys object.
+    MediaKeys* mediaKeys = new MediaKeys(executionContext(), m_keySystem, cdm.release());
+
+    // 2.5 Resolve promise with media keys.
+    resolve(mediaKeys);
+
+    // Note: As soon as the promise is resolved (or rejected), the
+    // ScriptPromiseResolver object (|this|) is freed. So access to
+    // any members will crash once the promise is fulfilled.
+}
+
+MediaKeySystemAccess::MediaKeySystemAccess(const String& keySystem)
+    : m_keySystem(keySystem)

[ddorwin, 2014/10/22 22:18:54]

I think it would be better if the request method created an Access object that
had some Chromium-side equivalent that contained any information, including the
key system, from the results of the request call. That is more consistent with
the spec design. It would also give us a place to put the createCDM() call.
Maybe MediaController should be a member?

This is fine for now, but we should look into this - maybe a FIXME?

[jrummell, 2014/10/23 01:20:02]

Done.

+{
+}
+
+MediaKeySystemAccess::~MediaKeySystemAccess()
+{
+}
+
+ScriptPromise MediaKeySystemAccess::createMediaKeys(ScriptState* scriptState)
+{
+    // From https://dvcs.w3.org/hg/html-media/raw-file/default/encrypted-media/encrypted-media.html#widl-MediaKeySystemAccess-createMediaKeys-Promise-MediaKeys
+    // When this method is invoked, the user agent must run the following steps:
+    // 1. Let promise be a new promise.
+    // 2. Asynchronously create and initialize the MediaKeys object.
+    // 3. Return promise.
+    return MediaKeysInitializer::create(scriptState, m_keySystem);
+}
+
+void MediaKeySystemAccess::trace(Visitor*)
+{
+}
+
+} // namespace blink