SF: Simplify getBestRefreshRate caching

Cache the arguments/result as std::pair by removing the out parameter
for GlobalSignals.

Bug: 185535769
Test: libsurfaceflinger_unittest
Change-Id: Ibfb2aa4ca327b378844554bcd96620f84fc0460a
diff --git a/services/surfaceflinger/Scheduler/RefreshRateConfigs.h b/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
index 7ef95f9..ade1787 100644
--- a/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
+++ b/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
@@ -20,6 +20,7 @@
 #include <numeric>
 #include <optional>
 #include <type_traits>
+#include <utility>
 
 #include <android-base/stringprintf.h>
 #include <gui/DisplayEventReceiver.h>
@@ -249,11 +250,10 @@
         }
     };
 
-    // Returns the refresh rate that best fits the given layers. outSignalsConsidered returns
-    // whether the refresh rate was chosen based on touch boost and/or idle timer.
-    RefreshRate getBestRefreshRate(const std::vector<LayerRequirement>&, GlobalSignals,
-                                   GlobalSignals* outSignalsConsidered = nullptr) const
-            EXCLUDES(mLock);
+    // Returns the refresh rate that best fits the given layers, and whether the refresh rate was
+    // chosen based on touch boost and/or idle timer.
+    std::pair<RefreshRate, GlobalSignals> getBestRefreshRate(const std::vector<LayerRequirement>&,
+                                                             GlobalSignals) const EXCLUDES(mLock);
 
     FpsRange getSupportedRefreshRateRange() const EXCLUDES(mLock) {
         std::lock_guard lock(mLock);
@@ -403,13 +403,8 @@
             const std::function<bool(const RefreshRate&)>& shouldAddRefreshRate,
             std::vector<const RefreshRate*>* outRefreshRates) REQUIRES(mLock);
 
-    std::optional<RefreshRate> getCachedBestRefreshRate(const std::vector<LayerRequirement>&,
-                                                        GlobalSignals,
-                                                        GlobalSignals* outSignalsConsidered) const
-            REQUIRES(mLock);
-
-    RefreshRate getBestRefreshRateLocked(const std::vector<LayerRequirement>&, GlobalSignals,
-                                         GlobalSignals* outSignalsConsidered) const REQUIRES(mLock);
+    std::pair<RefreshRate, GlobalSignals> getBestRefreshRateLocked(
+            const std::vector<LayerRequirement>&, GlobalSignals) const REQUIRES(mLock);
 
     // Returns the refresh rate with the highest score in the collection specified from begin
     // to end. If there are more than one with the same highest refresh rate, the first one is
@@ -497,14 +492,11 @@
     const Config mConfig;
     bool mSupportsFrameRateOverrideByContent;
 
-    struct GetBestRefreshRateInvocation {
-        std::vector<LayerRequirement> layerRequirements;
-        GlobalSignals globalSignals;
-        GlobalSignals outSignalsConsidered;
-        RefreshRate resultingBestRefreshRate;
+    struct GetBestRefreshRateCache {
+        std::pair<std::vector<LayerRequirement>, GlobalSignals> arguments;
+        std::pair<RefreshRate, GlobalSignals> result;
     };
-    mutable std::optional<GetBestRefreshRateInvocation> lastBestRefreshRateInvocation
-            GUARDED_BY(mLock);
+    mutable std::optional<GetBestRefreshRateCache> mGetBestRefreshRateCache GUARDED_BY(mLock);
 
     // Declare mIdleTimer last to ensure its thread joins before the mutex/callbacks are destroyed.
     std::mutex mIdleTimerCallbacksMutex;