Add buckets params to the binder latency atom

Original change: gerrit/14019215

Test: n/a - no functionality change
Bug: 180584913
Change-Id: I20d8f5632f76774cad64af30a6aa1f1ab172152f

core/java/com/android/internal/os/BinderLatencyObserver.java

@@ -157,7 +157,10 @@ public class BinderLatencyObserver {
                 FrameworkStatsLog.BINDER_LATENCY_REPORTED,
                 atom.getBytes(),
                 mPeriodicSamplingInterval,
-                1);
+                1,
+                mBucketCount,
+                mFirstBucketSize,
+                mBucketScaleFactor);
     }
 
     private void noteLatencyDelayed() {

core/proto/android/internal/binder_latency.proto

@@ -34,6 +34,7 @@ message Dims {
     UNKNOWN_PROCESS_SOURCE = 0;
     SYSTEM_SERVER = 1;
     TELEPHONY = 2;
+    BLUETOOTH = 3;
   }
 
   enum ServiceClassName {
@@ -74,4 +75,19 @@ message ApiStats {
   // Stores the count of samples for each bucket. The number of buckets and
   // their sizes are controlled server side with a flag.
   repeated int32 buckets = 3;
-}
+
+  // Params for histogram buckets.
+  // The number of buckets in the histogram. Store this value separately
+  // as the tail of empty buckets is truncated when stored in the proto to
+  // conserve space. Thus it is not possible to infer this value from there.
+  optional int32 bucket_count = 4;
+
+  // The size (upper bound) of the first bucket (used to avoid creating an
+  // excessive amount of small buckets). E.g. for first_bucket_size of 5, the
+  // first bucket will be [0, 5) and the second will be [5, 5 * scaleFactor).
+  optional int32 first_bucket_size = 5;
+
+  // The rate in which each consecutive bucket increases (before rounding).
+  // Implemented in: com.android.internal.os.BinderLatencyBuckets.
+  optional float scale_factor = 6;
+}