Add injectable version of Assert.isMainThread()

Introduces:
Execution.assertIsMainThread()
Execution.isMainThread()

Which can be injected and manipulated during tests

Bug: 186481467
Test: atest
Change-Id: Iba1cee95946452e3f74e55865d2a7fee2089798d

packages/SystemUI/src/com/android/systemui/util/concurrency/Execution.kt

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.systemui.util.concurrency
+
+import android.os.Looper
+import javax.inject.Inject
+
+/**
+ * Methods to check or assert that we're on the main thread
+ */
+interface Execution {
+    fun assertIsMainThread()
+    fun isMainThread(): Boolean
+}
+
+class ExecutionImpl @Inject constructor() : Execution {
+    private val mainLooper = Looper.getMainLooper()
+
+    override fun assertIsMainThread() {
+        if (!mainLooper.isCurrentThread) {
+            throw IllegalStateException("should be called from the main thread." +
+                    " Main thread name=" + mainLooper.thread.name +
+                    " Thread.currentThread()=" + Thread.currentThread().name)
+        }
+    }
+
+    override fun isMainThread(): Boolean {
+        return mainLooper.isCurrentThread
+    }
+}
+
+class FakeExecution : Execution {
+    var simulateMainThread = true
+
+    override fun assertIsMainThread() {
+        if (!simulateMainThread) {
+            throw IllegalStateException("should be called from the main thread")
+        }
+    }
+
+    override fun isMainThread(): Boolean {
+        return simulateMainThread
+    }
+}

packages/SystemUI/src/com/android/systemui/util/concurrency/GlobalConcurrencyModule.java

@@ -24,6 +24,8 @@ import com.android.systemui.dagger.qualifiers.Main;
 
 import java.util.concurrent.Executor;
 
+import javax.inject.Singleton;
+
 import dagger.Binds;
 import dagger.Module;
 import dagger.Provides;
@@ -40,7 +42,7 @@ public abstract class GlobalConcurrencyModule {
     @Binds
     public abstract ThreadFactory bindExecutorFactory(ThreadFactoryImpl impl);
 
-     /** Main Looper */
+    /** Main Looper */
     @Provides
     @Main
     public static  Looper provideMainLooper() {
@@ -67,4 +69,8 @@ public abstract class GlobalConcurrencyModule {
         return context.getMainExecutor();
     }
 
+    /** */
+    @Binds
+    @Singleton
+    public abstract Execution provideExecution(ExecutionImpl execution);
 }