stagefright: provide a custom key to prefer adaptive playback

Provide a custom key "prefer-adaptive-playback" that can be
set in MediaFormat by java apps or by Native players to
prefer adaptive-playback over dynamic buffering

Change-Id: Ic02fc9f1d68fd9803ec154498a86e2537efcce85
libstagefright: Smooth Streaming in OMXCodec

This change is to address startup latency during playback.

Set smooth-streaming mode from OMXCodec by default
if mm.enable.smoothstreaming property is enabled

When crop change is detected, save the target crop/stride and apply
them just before the buffer is (potentially) rendered.
Applying the updates right away may cause artifacts as buffers with
previous resolution are not rendered yet.

This approach assumes that there will not be a crop change within
the detection and application of current crop

CRs-Fixed: 584629

Change-Id: Ia164309edf1c51ed28b929deabecc53fc56cbf33
stagefright: Enable GraphicBuffer usage to decoder before querying formats

This lets the decoder publish appropriate color format based on surface
OR non-surface mode.

Change-Id: I567ae53d4d0dfa2abbf29e8196637a1da3e89969

Conflicts:
	media/libstagefright/OMXCodec.cpp
ACodec: Add video codec fallback logic

- Check while onAllocate if codec is capable of handling video
  resolution. If not fallback\retry other capable components in the
  list

Change-Id: I3203275be23651dbd9ad7a7397526ac601a3350a