SF: Move isWithin into implementation
Update the comment for the freeze timeline at the vsync time.

BUG: 343603085
Test: atest VSyncPredictorTest
Flag: com.android.graphics.surfaceflinger.flags.vrr_bugfix_24q4

Change-Id: I78cbe386983d7f8cefaab1d3b0e94f0a034815af
diff --git a/services/surfaceflinger/Scheduler/VSyncPredictor.h b/services/surfaceflinger/Scheduler/VSyncPredictor.h
index 66a7d71..64e1029 100644
--- a/services/surfaceflinger/Scheduler/VSyncPredictor.h
+++ b/services/surfaceflinger/Scheduler/VSyncPredictor.h
@@ -111,18 +111,7 @@
             Shared,  // Within timeline, shared with next timeline.
             Outside, // Outside of the timeline.
         };
-        VsyncOnTimeline isWithin(TimePoint vsync) {
-            const auto threshold = mIdealPeriod.ns() / 2;
-            if (!mValidUntil || vsync.ns() < mValidUntil->ns() - threshold) {
-                // if mValidUntil is absent then timeline is not frozen and
-                // vsync should be unique to that timeline.
-                return VsyncOnTimeline::Unique;
-            }
-            if (vsync.ns() > mValidUntil->ns() + threshold) {
-                return VsyncOnTimeline::Outside;
-            }
-            return VsyncOnTimeline::Shared;
-        }
+        VsyncOnTimeline isWithin(TimePoint vsync);
 
     private:
         nsecs_t snapToVsyncAlignedWithRenderRate(Model model, nsecs_t vsync);