This is the first use of IPCBlob: ClonedMessageData.
ClonedMessageData is used for BroadcastChannel, MessagePort and any
postMessage() communication. This patch changes StructuredCloneData in order to
use IPCBlob instead of PBlob.
BroadcastChannel has a custom way to manage Blobs because when the parent
receives them from a content process, it must send them to any other
BroadcastChild actor duplicating the serialization.
In JS StructuredClone BufferList<SystemAllocPolicy> is typedef'd to
JSStructuredCloneData and use everywhere in gecko that stores structured
clone data.
This patch changed some raw pointers to UniquePtr<JSStructuredCloneData>
and some to stack allocated JSStructuredCloneData for better life time
management. Some parameters or methods are deleted because of changing
to the new data structure.
MessagePortMessage now has the exactly same structure with
ClonedMessageData. Maybe in the future they can be consolidated.
MozReview-Commit-ID: 1IY9p5eKLgv
