feat: add SmartSharding option for Android instrumentation tests

PiperOrigin-RevId: 533270079

google/devtools/testing/v1/test_execution.proto

@@ -1213,6 +1213,9 @@ message ShardingOption {
     // Shards test cases into the specified groups of packages, classes, and/or
     // methods.
     ManualSharding manual_sharding = 2;
+
+    // Shards test based on previous test case timing records.
+    SmartSharding smart_sharding = 3;
   }
 }
 
@@ -1259,6 +1262,47 @@ message TestTargetsForShard {
   repeated string test_targets = 1;
 }
 
+// Shards test based on previous test case timing records.
+message SmartSharding {
+  // The amount of time tests within a shard should take.
+  //
+  // Default: 300 seconds (5 minutes).
+  // The minimum allowed: 120 seconds (2 minutes).
+  //
+  // The shard count is dynamically set based on time, up to the maximum shard
+  // limit (described below).  To guarantee at least one test case for each
+  // shard, the number of shards will not exceed the number of test cases. Shard
+  // duration will be exceeded if:
+  //   - The maximum shard limit is reached and there is more calculated test
+  //   time remaining to allocate into shards.
+  //   - Any individual test is estimated to be longer than the targeted shard
+  //   duration.
+  //
+  // Shard duration is not guaranteed because smart sharding uses test case
+  // history and default durations which may not be accurate. The rules for
+  // finding the test case timing records are:
+  //  - If the service has seen a test case in the last 30 days, the record
+  //  of the latest successful one will be used.
+  //  - For new test cases, the average duration of other known test cases will
+  //  be used.
+  //  - If there are no previous test case timing records available, the test
+  //  case is considered to be 15 seconds long by default.
+  //
+  // Because the actual shard duration can exceed the targeted shard duration,
+  // we recommend setting the targeted value at least 5 minutes less than the
+  // maximum allowed test timeout (45 minutes for physical devices and 60
+  // minutes for virtual), or using the custom test timeout value you set. This
+  // approach avoids cancelling the shard before all tests can finish.
+  //
+  // Note that there is a limit for maximum number of shards. When you select
+  // one or more physical devices, the number of shards must be <= 50. When you
+  // select one or more ARM virtual devices, it must be <= 100. When you select
+  // only x86 virtual devices, it must be <= 500. To guarantee at least one test
+  // case for per shard, the number of shards will not exceed the number of test
+  // cases. Each shard created will count toward daily test quota.
+  google.protobuf.Duration targeted_shard_duration = 1;
+}
+
 // Output only. Details about the shard.
 message Shard {
   // Output only. The index of the shard among all the shards.