Fix shim layer bugs for Sensors HIDL wrapper.

i) Increase the number of default threads to 2.
ii) Handle the flush complete event correctly.

Bug: 35189074
Bug: 35067266

Test: Test that sensors work in both binderized and passthrough modes.
      Ensure that camera photosphere works.

Change-Id: Ic8dadf03395b4e96092ae962cf790c93d65a1c8d
diff --git a/sensors/1.0/default/service.cpp b/sensors/1.0/default/service.cpp
index 5bcfe4b..65f6d81 100644
--- a/sensors/1.0/default/service.cpp
+++ b/sensors/1.0/default/service.cpp
@@ -23,5 +23,9 @@
 using android::hardware::defaultPassthroughServiceImplementation;
 
 int main() {
-    return defaultPassthroughServiceImplementation<ISensors>();
+    /* Sensors framework service needs at least two threads.
+     * One thread blocks on a "poll"
+     * The second thread is needed for all other HAL methods.
+     */
+    return defaultPassthroughServiceImplementation<ISensors>(2);
 }