Merge "[HWUI] Add null check for CanvasContext" into rvc-dev am: c2e20c4b...

        FrameInfo* forthBehind = mLast4FrameInfos.front().first;

        int64_t composedFrameId = mLast4FrameInfos.front().second;

        nsecs_t acquireTime = -1;

        if (mNativeSurface) {

            native_window_get_frame_timestamps(mNativeSurface->getNativeWindow(), composedFrameId,

                                               nullptr, &acquireTime, nullptr, nullptr, nullptr,

                                               nullptr, nullptr, nullptr, nullptr);

        }

        // Ignore default -1, NATIVE_WINDOW_TIMESTAMP_INVALID and NATIVE_WINDOW_TIMESTAMP_PENDING

        forthBehind->set(FrameInfoIndex::GpuCompleted) = acquireTime > 0 ? acquireTime : -1;

        mJankTracker.finishGpuDraw(*forthBehind);