CDD: Requirement updates for the assistant

With Android 6.0 there are new APIs allowing assistant to be more
aware of the context of the foreground application. 

To ensure a wide-spread adoption of the feature by cross-device
consistency and to protect end-user privacy, the change introduces:

- stronger language on allowed gestures to start the assistant
- mandatory requirement on how to indicate the end user of context

Bug: 20012526
Bug: 23360409

Change-Id: I2debcef9a6d50cc2341734e0e064c8a6f940f65a
1 file changed