Merge "media: clarify that flush() is not supported for encoders." into tm-dev...

Merge "media: clarify that flush() is not supported for encoders." into tm-dev am: 381a3b66 am: 946aeccb am: e113210f

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/18590094



Change-Id: I2ca97109a024644fa5059450d4013706384b8127
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>