Basic use implementation for MediaStream from Canvas: captureStream()

third_party/WebKit/Source/modules/mediacapturefromelement/CanvasCaptureMediaStream.h

Index: third_party/WebKit/Source/modules/mediacapturefromelement/CanvasCaptureMediaStream.h
diff --git a/third_party/WebKit/Source/modules/mediacapturefromelement/CanvasCaptureMediaStream.h b/third_party/WebKit/Source/modules/mediacapturefromelement/CanvasCaptureMediaStream.h
new file mode 100644
index 0000000000000000000000000000000000000000..5f78a87909b922791bc35fafceb0ba5152eb0839
--- /dev/null
+++ b/third_party/WebKit/Source/modules/mediacapturefromelement/CanvasCaptureMediaStream.h
@@ -0,0 +1,36 @@
+// Copyright 2015 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.
+
+#ifndef CanvasCaptureMediaStream_h
+#define CanvasCaptureMediaStream_h
+
+#include "core/html/canvas/CanvasDrawListener.h"
+#include "modules/mediastream/MediaStream.h"
+#include "platform/heap/Handle.h"
+
+namespace blink {
+
+class HTMLCanvasElement;
+class WebCanvasCaptureHandler;
+
+class CanvasCaptureMediaStream final : public MediaStream {
+    DEFINE_WRAPPERTYPEINFO();
+    USING_GARBAGE_COLLECTED_MIXIN(CanvasCaptureMediaStream);
+
+public:
+    ~CanvasCaptureMediaStream();
+    static CanvasCaptureMediaStream* create(MediaStreamDescriptor*, HTMLCanvasElement&, const PassOwnPtr<WebCanvasCaptureHandler>&);

[peria, 2015/11/24 05:50:22]

It is not recommended to pass an argument by non-const reference.  Please use a
raw pointer or PassRefPtrWillBeRawPtr<HTMLCanvasElement> instead.

[peria, 2015/11/24 05:50:22]

nit: PassOwnPtr<> does not require &.

[emircan, 2015/11/24 22:16:51]

Done but there are problems. See the answer below.

+    DECLARE_VIRTUAL_TRACE();
+    HTMLCanvasElement* canvas() const;
+    void requestFrame();
+
+private:
+    CanvasCaptureMediaStream(MediaStreamDescriptor*, HTMLCanvasElement&, const PassOwnPtr<WebCanvasCaptureHandler>&);

[peria, 2015/11/24 05:50:22]

ditto.

[emircan, 2015/11/24 22:16:51]

Done.

+    RawPtrWillBeMember<HTMLCanvasElement> m_canvasElement;

[peria, 2015/11/24 05:50:22]

I'm not sure how m_canvasElement's lifetime is managed, but shouldn't this be
RefPtrWillBeMember<>?

[emircan, 2015/11/24 22:16:51]

RefPtrWillBeMember makes sense to me as well and I made the change. However, I
get the following error during destruction in this way. Is it proper to use
adoptRef() in HTMLCanvasElementCapture::captureStream() to create reference to
the class. Do you see any other issue?

https://paste.googleplex.com/6030890702471168

+    OwnPtrWillBeMember<CanvasDrawListener> m_drawListener;

[peria, 2015/11/24 05:50:22]

s/OwnPtrWillBe//.

[emircan, 2015/11/24 22:16:51]

Done.

+};
+
+} // namespace blink
+
+#endif