MediaRecorder: update to spec (2/3)

third_party/WebKit/Source/modules/mediarecorder/MediaRecorder.cpp

Index: third_party/WebKit/Source/modules/mediarecorder/MediaRecorder.cpp
diff --git a/third_party/WebKit/Source/modules/mediarecorder/MediaRecorder.cpp b/third_party/WebKit/Source/modules/mediarecorder/MediaRecorder.cpp
index d84100f9a9833c78e507ddaa57471df3f2888181..767bac623260d947345c21a5960ccbc531ed4c8f 100644
--- a/third_party/WebKit/Source/modules/mediarecorder/MediaRecorder.cpp
+++ b/third_party/WebKit/Source/modules/mediarecorder/MediaRecorder.cpp
@@ -5,6 +5,7 @@
 #include "config.h"
 #include "modules/mediarecorder/MediaRecorder.h"
 
+#include "bindings/core/v8/Dictionary.h"
 #include "core/dom/DOMError.h"
 #include "core/fileapi/Blob.h"
 #include "core/frame/ConsoleTypes.h"
@@ -41,24 +42,24 @@ String stateToString(MediaRecorder::State state)
 
 MediaRecorder* MediaRecorder::create(ExecutionContext* context, MediaStream* stream, ExceptionState& exceptionState)
 {
-    MediaRecorder* recorder = new MediaRecorder(context, stream, String(), exceptionState);
+    MediaRecorder* recorder = new MediaRecorder(context, stream, MediaRecorderOptions(), exceptionState);
     recorder->suspendIfNeeded();
 
     return recorder;
 }
 
-MediaRecorder* MediaRecorder::create(ExecutionContext* context, MediaStream* stream,  const String& mimeType, ExceptionState& exceptionState)
+MediaRecorder* MediaRecorder::create(ExecutionContext* context, MediaStream* stream,  const MediaRecorderOptions& options, ExceptionState& exceptionState)
 {
-    MediaRecorder* recorder = new MediaRecorder(context, stream, mimeType, exceptionState);
+    MediaRecorder* recorder = new MediaRecorder(context, stream, options, exceptionState);
     recorder->suspendIfNeeded();
 
     return recorder;
 }
 
-MediaRecorder::MediaRecorder(ExecutionContext* context, MediaStream* stream, const String& mimeType, ExceptionState& exceptionState)
+MediaRecorder::MediaRecorder(ExecutionContext* context, MediaStream* stream, const MediaRecorderOptions& options, ExceptionState& exceptionState)
     : ActiveDOMObject(context)
     , m_stream(stream)
-    , m_mimeType(mimeType)
+    , m_mimeType(options.mimeType())
     , m_stopped(true)
     , m_ignoreMutedMedia(true)
     , m_state(State::Inactive)
@@ -158,20 +159,18 @@ void MediaRecorder::requestData(ExceptionState& exceptionState)
     writeData(nullptr /* data */, 0 /* length */, true /* lastInSlice */);
 }
 
-String MediaRecorder::canRecordMimeType(const String& mimeType)
+bool MediaRecorder::isTypeSupported(const String& type)

[philipj_slow, 2015/12/11 08:29:03]

Can you use this in the constructor, where the "the type provided ... is
unsupported" exception is thrown? That should cause an exception to be thrown by
default, highlighting the issue of having "" as the default value of mimeType.

If there needs to be any divergence between when
MediaRecorder.isTypeSupported(x) returns false and when new MediaRecorder(ms, {
mimeType: x }) throws an exception, can you document them clearly? My guess is
that there need be no such differences.

[philipj_slow, 2015/12/18 20:18:10]

I've filed https://code.google.com/p/chromium/issues/detail?id=571107

 {
     RawPtr<WebMediaRecorderHandler> handler = Platform::current()->createMediaRecorderHandler();
     if (!handler)
-        return emptyString();
-
-    // MediaRecorder canRecordMimeType() MUST return 'probably' "if the UA is
-    // confident that mimeType represents a type that it can record" [1], but a
-    // number of reasons could prevent the recording from happening as expected,
-    // so 'maybe' is a better option: "Implementors are encouraged to return
-    // "maybe" unless the type can be confidently established as being supported
-    // or not.". Hence this method returns '' or 'maybe', never 'probably'.
-    // [1] http://w3c.github.io/mediacapture-record/MediaRecorder.html#methods
-    return handler->canSupportMimeType(mimeType) ? "maybe" : emptyString();
+        return false;
+
+    // If true is returned from this method, it only indicates that the
+    // MediaRecorder implementation is capable of recording Blob objects for the
+    // specified MIME type. Recording may still fail if sufficient resources are
+    // not available to support the concrete media encoding.
+    // [1] https://w3c.github.io/mediacapture-record/MediaRecorder.html#methods
+    return handler->canSupportMimeType(type);
 }
 
 const AtomicString& MediaRecorder::interfaceName() const