void Composer::setDisplaySurface(const sp<IBinder>& token,
        const sp<ISurfaceTexture>& surface) {
    Mutex::Autolock _l(mLock);
    DisplayState& s(getDisplayStateLocked(token));
    s.surface = surface;
    s.what |= DisplayState::eSurfaceChanged;
}
void Composer::setDisplayLayerStack(const sp<IBinder>& token,
        uint32_t layerStack) {
    Mutex::Autolock _l(mLock);
    DisplayState& s(getDisplayStateLocked(token));
    s.layerStack = layerStack;
    s.what |= DisplayState::eLayerStackChanged;
}
void Composer::setDisplaySurface(const sp<IBinder>& token,
        const sp<IGraphicBufferProducer>& bufferProducer) {
    Mutex::Autolock _l(mLock);
    DisplayState& s(getDisplayStateLocked(token));
    s.surface = bufferProducer;
    s.what |= DisplayState::eSurfaceChanged;
}
void Composer::setDisplayProjection(const sp<IBinder>& token,
        uint32_t orientation,
        const Rect& layerStackRect,
        const Rect& displayRect) {
    Mutex::Autolock _l(mLock);
    DisplayState& s(getDisplayStateLocked(token));
    s.orientation = orientation;
    s.viewport = layerStackRect;
    s.frame = displayRect;
    s.what |= DisplayState::eDisplayProjectionChanged;
    mForceSynchronous = true; // TODO: do we actually still need this?
}