Pass ProductId+VendorId+Source info to LatencyTracker

Currently InputEventLatencySketch captures the aggregated latency over
all devices, and it doesn't capture per-device latency.
In order to capture latency metrics per device, we track the timeline
for latency information for each Product Id, Vendor Id and Source
individually.

Bug: 270049345
Test: atest inputflinger_tests:LatencyTrackerTest
Change-Id: Ic3265e25ff95266e8cfe8542d4f4afb7b6ac16b1
diff --git a/services/inputflinger/InputDeviceMetricsSource.h b/services/inputflinger/InputDeviceMetricsSource.h
index 3ac91c8..a6be8f4 100644
--- a/services/inputflinger/InputDeviceMetricsSource.h
+++ b/services/inputflinger/InputDeviceMetricsSource.h
@@ -47,6 +47,8 @@
 
     ftl_first = UNKNOWN,
     ftl_last = TRACKBALL,
+    // Used by latency fuzzer
+    kMaxValue = ftl_last
 };
 
 /** Returns the InputDeviceUsageSource that corresponds to the key event. */