SF: Encapsulate frame targeting

Introduce FrameTargeter to isolate a display's per-frame metrics around
past/upcoming deadline targets. The Scheduler updates the FrameTargeter
on frame begin/end, whereas ICompositor (concretely SurfaceFlinger) has
read-only access via the FrameTarget interface.

For now, only instantiate the pacesetter's FrameTargeter.

The only functional change is that `earliestPresentTime` now takes into
account the case of targeting two VSYNCs ahead.

Bug: 241285475
Bug: 241285191
Test: Perfetto
Test: dumpsys SurfaceFlinger --scheduler
Test: atest libscheduler_test:FrameTargeterTest
Change-Id: Idf9f43b37f3479c94a478d154eaa46f43e0c6c9d
diff --git a/services/surfaceflinger/Scheduler/Scheduler.h b/services/surfaceflinger/Scheduler/Scheduler.h
index f13c878..4e1faf5 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.h
+++ b/services/surfaceflinger/Scheduler/Scheduler.h
@@ -35,6 +35,7 @@
 #include <ftl/fake_guard.h>
 #include <ftl/optional.h>
 #include <scheduler/Features.h>
+#include <scheduler/FrameTargeter.h>
 #include <scheduler/Time.h>
 #include <scheduler/VsyncConfig.h>
 #include <ui/DisplayId.h>
@@ -249,9 +250,11 @@
         return std::const_pointer_cast<VsyncSchedule>(std::as_const(*this).getVsyncSchedule(idOpt));
     }
 
+    const FrameTarget& pacesetterFrameTarget() { return mPacesetterFrameTargeter.target(); }
+
     // Returns true if a given vsync timestamp is considered valid vsync
     // for a given uid
-    bool isVsyncValid(TimePoint expectedVsyncTimestamp, uid_t uid) const;
+    bool isVsyncValid(TimePoint expectedVsyncTime, uid_t uid) const;
 
     bool isVsyncInPhase(TimePoint expectedVsyncTime, Fps frameRate) const;
 
@@ -441,6 +444,8 @@
     ftl::Optional<PhysicalDisplayId> mPacesetterDisplayId GUARDED_BY(mDisplayLock)
             GUARDED_BY(kMainThreadContext);
 
+    FrameTargeter mPacesetterFrameTargeter{mFeatures.test(Feature::kBackpressureGpuComposition)};
+
     ftl::Optional<DisplayRef> pacesetterDisplayLocked() REQUIRES(mDisplayLock) {
         return static_cast<const Scheduler*>(this)->pacesetterDisplayLocked().transform(
                 [](const Display& display) { return std::ref(const_cast<Display&>(display)); });