App freezer stat logs

Bug: 143308662
Test: westworld tests on local device (go/westworld-local-development)
Change-Id: I0f3f966b6057a3465a1e686f93caf28cd7247b2c

cmds/statsd/src/atoms.proto

@@ -391,6 +391,7 @@ message Atom {
         WifiHealthStatReported wifi_health_stat_reported = 251 [(module) = "wifi"];
         WifiFailureStatReported wifi_failure_stat_reported = 252 [(module) = "wifi"];
         WifiConnectionResultReported wifi_connection_result_reported = 253 [(module) = "wifi"];
+        AppFreezeChanged app_freeze_changed = 254 [(module) = "framework"];
         SdkExtensionStatus sdk_extension_status = 354;
     }
 
@@ -8366,3 +8367,28 @@ message SdkExtensionStatus {
     // "Failed" here can mean a symbol that wasn't meant to be visible was, or the other way around.
     optional int32 failed_call_symbol = 3;
 }
+
+/**
+ * Logs when an app is frozen or unfrozen.
+ *
+ * Logged from:
+ *   frameworks/base/services/core/java/com/android/server/am/CachedAppOptimizer.java
+ */
+message AppFreezeChanged {
+  // The type of event.
+  enum Action {
+    UNKNOWN = 0;
+    FREEZE_APP = 1;
+    UNFREEZE_APP = 2;
+  }
+  optional Action action = 1;
+
+  // Pid of the process being frozen.
+  optional int32 pid = 2;
+
+  // Name of the process being frozen.
+  optional string process_name = 3;
+
+  // Time since last unfrozen.
+  optional int64 time_unfrozen_millis = 4;
+}