tree 42b40571c3ad901d402104dd86e59e91fa969f3e
parent 0c689d47be3e7ad80d69c183958d32c210196496
author Ramkumar Radhakrishnan <ramkumar@codeaurora.org> 1501562266 -0700
committer Gerrit - the friendly Code Review server <code-review@localhost> 1501878685 -0700

hwc2: Wait for RegisterCallback() from SF before sending events.

Surfaceflinger registers callback functions to be called from
hwcomposer on specific events like hotplug, vsync and screen refresh.
since surfaceflinger and hwcomposer are two different processes that
can run asynchronously. This causes hwcomposer to send an event to
surfaceflinger before surfaceflinger registers callback and results
in undefined behavior. So wait for callbacks to get registered by
surfaceflinger and send an event to surfacelinger.

Change-Id: I288e4d7dde8179cb4a119cdedad2877344c06dae
CRs-Fixed: 2085392