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This introduces basic infrastructure that should allow content providers holding complex data to perform on-demand conversion of their data to streams of various types. It is achieved through two new content provider APIs, one to interrogate the possible stream MIME types the provider can return, and the other to request a stream of data in a particular MIME type. Because implementations of this will often need to do on-demand data conversion, there is also a utility intoduced in ContentProvider for subclasses to easily run a function to write data into a pipe that is read by the client. This feature is mostly intended for cut and paste and drag and drop, as the complex data interchange allowing the source and destination to negotiate data types and copy (possible large) data between them. However because it is fundamental facility of ContentProvider, it can be used in other places, such as for more advanced GET_CONTENT data exchanges. An example implementation of this would be in ContactsProvider, which can now provider a data stream when a client opens certain pieces of it data, to return data as flat text, a vcard, or other format. Change-Id: I58627ea4ed359aa7cf2c66274adb18306c209cb2