Move toggling of kernel idle timer to SF

Idle timer is toggled from the SF code using the following logic:
- If the device policy refresh rate min = max, we turn off the timer.
- If the device policy refresh rate min > the device min,
  we turn off the timer.
- Do not toggle the timer if deviceMin == policyMin.
- Timer is on in all other cases.

Bug: 140204874
Bug: 158012424
Bug: 145561154
Test: atest SurfaceFlinger_test
Test: atest libsurfaceflinger_unittest
Test: Select force 90hz through Developer Settings. Toggles timer off.
Test: Low brightness zone. Toggles timer off.
Change-Id: I9858765861a3b13e11c3930be8f77d85dae6c0c0
diff --git a/services/surfaceflinger/Scheduler/RefreshRateConfigs.h b/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
index 584a5e7..8a51b85 100644
--- a/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
+++ b/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
@@ -82,6 +82,8 @@
             return configId != other.configId || hwcConfig != other.hwcConfig;
         }
 
+        bool operator<(const RefreshRate& other) const { return getFps() < other.getFps(); }
+
         bool operator==(const RefreshRate& other) const { return !(*this != other); }
 
     private:
@@ -271,6 +273,17 @@
     RefreshRateConfigs(const std::vector<std::shared_ptr<const HWC2::Display::Config>>& configs,
                        HwcConfigIndexType currentConfigId);
 
+    // Class to enumerate options around toggling the kernel timer on and off. We have an option
+    // for no change to avoid extra calls to kernel.
+    enum class KernelIdleTimerAction {
+        NoChange, // Do not change the idle timer.
+        TurnOff,  // Turn off the idle timer.
+        TurnOn    // Turn on the idle timer.
+    };
+    // Checks whether kernel idle timer should be active depending the policy decisions around
+    // refresh rates.
+    KernelIdleTimerAction getIdleTimerAction() const;
+
 private:
     friend class RefreshRateConfigsTest;