[Dolphin] Clean up config proto.

Right now, we don't have any important experiments running. I'm taking
this as a chance to do some cleanup of the recurrence ranker config proto
now that our API is mostly stable. This CL renumbers the fields and
removes some that were reserved. This changes the config proto hash and
will result in all on-disk models being thrown out.

Bug: 921444
Change-Id: I35283117e489f58f57cea1cb842a43c5c02de44c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1670284Reviewed-by: Charles . <charleszhao@chromium.org>
Commit-Queue: Tony Yeoman <tby@chromium.org>
Cr-Commit-Position: refs/heads/master@{#671569}

chrome/browser/ui/app_list/search/search_result_ranker/recurrence_ranker_config.proto

@@ -13,17 +13,12 @@ package app_list;
 // Warning: this cannot contain any map fields, as they cannot be relied upon
 // for a consistent hash.
 message RecurrenceRankerConfigProto {
-  // Fields with IDs 1 (target_limit) and 2 (target_decay_coeff) have been
-  // deleted.
-  reserved 1;
-  reserved 2;
+  required uint32 min_seconds_between_saves = 1;
 
-  required uint32 min_seconds_between_saves = 3;
-
-  required uint32 target_limit = 4;
-  required float target_decay = 5;
-  required uint32 condition_limit = 6;
-  required float condition_decay = 7;
+  required uint32 target_limit = 2;
+  required float target_decay = 3;
+  required uint32 condition_limit = 4;
+  required float condition_decay = 5;
 
   // Config for a fake predictor, used for testing.
   message FakePredictorConfig {}
@@ -34,19 +29,17 @@ message RecurrenceRankerConfigProto {
 
   // Config for a frecency predictor.
   message ZeroStateFrecencyPredictorConfig {
-    // Field 201 (target_limit) has been deleted.
-    reserved 201;
     // The frecency parameter used to control the frequency-recency tradeoff
     // that determines when targets are removed. Must be in [0.5, 1.0], with 0.5
     // meaning only-recency and 1.0 meaning only-frequency.
-    required float decay_coeff = 202;
+    required float decay_coeff = 1;
   }
 
   message ZeroStateHourBinPredictorConfig {
     // The decay coeffficient number that control the decay rate. The decay is
     // once a week.
-    required float weekly_decay_coeff = 301;
-    map<int32, float> bin_weights_map = 302;
+    required float weekly_decay_coeff = 1;
+    map<int32, float> bin_weights_map = 2;
   }
 
   // The choice of which kind of predictor to use, and its configuration.