Add additional tests for PowerAdvisor

Adds additional tests for PowerAdvisor functionality regarding
timing and multidisplay

Bug: b/241465879
Test: atest
libsurfaceflinger_unittest:libsurfaceflinger_unittest.PowerAdvisorTest

Change-Id: I833e91efb5608d5972220c679a061c9bb51372fa
diff --git a/services/surfaceflinger/DisplayHardware/PowerAdvisor.h b/services/surfaceflinger/DisplayHardware/PowerAdvisor.h
index 71a1f8c..6e25f78 100644
--- a/services/surfaceflinger/DisplayHardware/PowerAdvisor.h
+++ b/services/surfaceflinger/DisplayHardware/PowerAdvisor.h
@@ -154,6 +154,13 @@
     void setTotalFrameTargetWorkDuration(nsecs_t targetDuration) override;
 
 private:
+    friend class PowerAdvisorTest;
+
+    // Tracks if powerhal exists
+    bool mHasHal = true;
+    // Holds the hal wrapper for getPowerHal
+    std::unique_ptr<HalWrapper> mHalWrapper GUARDED_BY(mPowerHalMutex) = nullptr;
+
     HalWrapper* getPowerHal() REQUIRES(mPowerHalMutex);
     bool mReconnectPowerHal GUARDED_BY(mPowerHalMutex) = false;
     std::mutex mPowerHalMutex;