Add Fps class

Add a class to wrap a fps value. This is useful because across
the code we
 - convert between vsyncPeriod and fps
 - compare with tolerance (this ensures we use consistent tolerance)
 - consistent toString method

Bug: 159590486
Test: presubmit
Change-Id: Iebb77a33a2f822056642aa61bd6fac6514aa656d
diff --git a/services/surfaceflinger/tests/unittests/SetFrameRateTest.cpp b/services/surfaceflinger/tests/unittests/SetFrameRateTest.cpp
index 5278641..c47b141 100644
--- a/services/surfaceflinger/tests/unittests/SetFrameRateTest.cpp
+++ b/services/surfaceflinger/tests/unittests/SetFrameRateTest.cpp
@@ -108,11 +108,12 @@
  */
 class SetFrameRateTest : public ::testing::TestWithParam<std::shared_ptr<LayerFactory>> {
 protected:
-    const FrameRate FRAME_RATE_VOTE1 = FrameRate(67.f, FrameRateCompatibility::Default);
-    const FrameRate FRAME_RATE_VOTE2 = FrameRate(14.f, FrameRateCompatibility::ExactOrMultiple);
-    const FrameRate FRAME_RATE_VOTE3 = FrameRate(99.f, FrameRateCompatibility::NoVote);
-    const FrameRate FRAME_RATE_TREE = FrameRate(0, FrameRateCompatibility::NoVote);
-    const FrameRate FRAME_RATE_NO_VOTE = FrameRate(0, FrameRateCompatibility::Default);
+    const FrameRate FRAME_RATE_VOTE1 = FrameRate(Fps(67.f), FrameRateCompatibility::Default);
+    const FrameRate FRAME_RATE_VOTE2 =
+            FrameRate(Fps(14.f), FrameRateCompatibility::ExactOrMultiple);
+    const FrameRate FRAME_RATE_VOTE3 = FrameRate(Fps(99.f), FrameRateCompatibility::NoVote);
+    const FrameRate FRAME_RATE_TREE = FrameRate(Fps(0.f), FrameRateCompatibility::NoVote);
+    const FrameRate FRAME_RATE_NO_VOTE = FrameRate(Fps(0.f), FrameRateCompatibility::Default);
 
     SetFrameRateTest();