Changed BuildTargetChecker to use RunOnMainThread.

Also, fixed use of Unity methods from a static constructor.
This *may* have been contributing to a hang when the version handler plugin
starts up.

Bug: 131100117
Change-Id: I6dc4c2252b470520275b3e1763bb006ab3869f44

Author: Stewart Miles

source/VersionHandlerImpl/src/VersionHandlerImpl.cs

@@ -1981,39 +1981,25 @@ internal static string[] OnWillSaveAssets(string[] paths) {
     /// </summary>
     [InitializeOnLoad]
     internal class BuildTargetChecker {
+        private const double POLL_INTERVAL_MILLISECONDS = 1000.0f;
         private static BuildTarget? lastKnownBuildTarget = null;
-        private static int ticksSinceLastCheck = 0;
-        private static int ticksBetweenChecks = 60;
-
 
         static BuildTargetChecker() {
-            HandleSettingsChanged();
+            RunOnMainThread.Run(HandleSettingsChanged, runNow: false);
         }
 
-        public static void HandleSettingsChanged() {
-            RunOnMainThread.OnUpdate -= CheckBuildTarget;
-            if (Enabled && RenameToDisableFilesEnabled) {
-                RunOnMainThread.OnUpdate += CheckBuildTarget;
-            }
-        }
+        // NOTE: This should only be called from the main thread.
+        public static void HandleSettingsChanged() { CheckBuildTarget(); }
 
         private static void CheckBuildTarget() {
-            ticksSinceLastCheck++;
-            if (ticksSinceLastCheck < ticksBetweenChecks) {
-                return;
-            }
-
-            if (!Enabled || !RenameToDisableFilesEnabled) {
-                RunOnMainThread.OnUpdate -= CheckBuildTarget;
-            }
-
             var newBuildTarget = EditorUserBuildSettings.activeBuildTarget;
             if (lastKnownBuildTarget == null || newBuildTarget != lastKnownBuildTarget) {
                 lastKnownBuildTarget = newBuildTarget;
                 HandleBuildTargetChanged(newBuildTarget);
             }
-
-            ticksSinceLastCheck = 0;
+            if (Enabled && RenameToDisableFilesEnabled && !ExecutionEnvironment.InBatchMode) {
+                RunOnMainThread.Schedule(CheckBuildTarget, POLL_INTERVAL_MILLISECONDS);
+            }
         }
 
         private static void HandleBuildTargetChanged(BuildTarget newBuildTarget) {

source/VersionHandlerImpl/test/activation/Assets/PlayServicesResolver/Editor/TestEnabledCallback.cs

@@ -69,6 +69,8 @@ private static bool SetInitialized() {
     /// Register a method to call when the Version Handler has enabled all plugins in the project.
     /// </summary>
     static TestEnabledCallback() {
+        // Disable stack traces for more condensed logs.
+        UnityEngine.Application.stackTraceLogType = UnityEngine.StackTraceLogType.None;
         UnityEngine.Debug.Log("Ensure plugin components are not loaded.");
         if (!SetInitialized()) {
             foreach (var kv in EntryPoints) {