Add conversation ID into the filter so findMessages() can return messages for a given conversation

[airpingu]

In the current Mozilla implementation [1], our filter can accept the conversation ID. We found this is useful because findMessages() can thus return messages for a given conversation.

A real use case is when the user taps on a conversation in the conversation list, it sounds redundant for findMessages() to filter the messages again because we've already done that when calling findConversations() to generate the conversation list.
Since we're sure which conversation we're looking for, why not just finding messages given that specific conversation ID?

To do this, we probably need to add a new property conversationID in the {Sms,Mms}Message structure as well.

[1] https://hg.mozilla.org/mozilla-central/file/aebdc69b02e5/dom/mobilemessage/interfaces/nsIDOMSmsFilter.idl

Gene

[airpingu]

Btw, if we're going to switch the conversation DB to local by using DataStore API then this is no issue.

[zolkis]

Everything related to the data model needs to be revisited. In SysApps scope, I believe the API should provide the protocol abstractions, plus descriptions of related data (messages), but how to store or retrieve the data should perhaps be in a different API. Same applies for Telephony.

[zolkis]

See also #91