[GStreamer] Add sharedBuffer utility to GstMappedBuffer, and a testsuite

[GStreamer] Add sharedBuffer utility to GstMappedBuffer, and a testsuite
https://bugs.webkit.org/show_bug.cgi?id=192977

Reviewed by Carlos Garcia Campos.

Source/WebCore:

Add a utility method on GstMappedBuffer to return a SharedBuffer
view over the mapped data with no copies.

This patch also introduces a new gstreamer port API test
directory, and includes some tests for GstMappedBuffer.

New tests in the API section.

* platform/SharedBuffer.cpp: Add a new overload for
GstMappedBuffer that allows sharing the mapped GStreamer buffers
with zero copies.
(WebCore::SharedBuffer::create):
(WebCore::SharedBuffer::SharedBuffer):
(WebCore::SharedBuffer::DataSegment::data const):
(WebCore::SharedBuffer::DataSegment::size const):
* platform/SharedBuffer.h:
* platform/audio/gstreamer/WebKitWebAudioSourceGStreamer.cpp:
(webKitWebAudioSrcAllocateBuffersAndRenderAudio): Update to new
API.
* platform/graphics/gstreamer/GStreamerCommon.cpp:
(WebCore::GstMappedBuffer::createSharedBuffer): Return a shared
buffer sharing this mapped buffer. The buffer must be shareable to
use this method.
* platform/graphics/gstreamer/GStreamerCommon.h:
(WebCore::GstMappedBuffer::create): Make GstMappedBuffer RefCounted
(WebCore::GstMappedBuffer::~GstMappedBuffer):
(WebCore::GstMappedBuffer::data):
(WebCore::GstMappedBuffer::data const):
(WebCore::GstMappedBuffer::size const):
(WebCore::GstMappedBuffer::isSharable const): New predicate to
check whether this buffer can be shared (i.e., is not writable)
(WebCore::GstMappedBuffer::GstMappedBuffer):
(WebCore::GstMappedBuffer::operator bool const): Deleted.
* platform/graphics/gstreamer/InbandTextTrackPrivateGStreamer.cpp:
(WebCore::InbandTextTrackPrivateGStreamer::notifyTrackOfSample):
Update to use new API.
* platform/graphics/gstreamer/eme/GStreamerEMEUtilities.h:
(WebCore::InitData::InitData): Ditto.
* platform/graphics/gstreamer/eme/WebKitClearKeyDecryptorGStreamer.cpp:
(webKitMediaClearKeyDecryptorFindAndSetKey): Ditto.
(webKitMediaClearKeyDecryptorDecrypt): Ditto.
* platform/mediastream/gstreamer/MockGStreamerAudioCaptureSource.cpp:
(WebCore::WrappedMockRealtimeAudioSource::render): Ditto.
* platform/mediastream/gstreamer/RealtimeOutgoingAudioSourceLibWebRTC.cpp:
(WebCore::RealtimeOutgoingAudioSourceLibWebRTC::pullAudioData): Ditto.
* platform/mediastream/gstreamer/RealtimeOutgoingVideoSourceLibWebRTC.cpp:
(WebCore::RealtimeOutgoingVideoSourceLibWebRTC::createBlackFrame): Ditto.
* platform/mediastream/libwebrtc/GStreamerVideoEncoderFactory.cpp:
(WebCore::GStreamerVideoEncoder::Fragmentize): Ditto.

Tools:

* TestWebKitAPI/PlatformGTK.cmake: Build the new GStreamer test harness
* TestWebKitAPI/PlatformWPE.cmake: Ditto.
* TestWebKitAPI/Tests/WebCore/gstreamer/GStreamerTest.cpp: Added.
(TestWebKitAPI::GStreamerTest::SetUp):
(TestWebKitAPI::GStreamerTest::TearDown):
* TestWebKitAPI/Tests/WebCore/gstreamer/GStreamerTest.h: Added.
* TestWebKitAPI/Tests/WebCore/gstreamer/GstMappedBuffer.cpp: Added.
(TestWebKitAPI::TEST_F):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@239921 268f45cc-cd09-0410-ab3c-d52691b4dbfc