Move utilities to libs/net

These files used to be in the network stack directory, but the libs
directory is a much more suitable place for them.

Also fix a typo : ConcurrentIntepreter → ConcurrentInterpreter

Also move {FdEvents,Packet}Reader to internal annotations. That's
what they should have been using in the first place anyway.

Note that this does not fix preupload issues reported by
checkstyle to make review easier. The fixes are in a followup
patch to this one.

Test: checkbuild
Change-Id: I675077fd42cbb092c0e6bd56571f2fc022e582fd

staticlibs/devicetests/com/android/testutils/HandlerUtils.kt

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2019 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.testutils
+
+import android.os.ConditionVariable
+import android.os.Handler
+import android.os.HandlerThread
+import java.util.concurrent.Executor
+import kotlin.system.measureTimeMillis
+import kotlin.test.fail
+
+/**
+ * Block until the specified Handler or HandlerThread becomes idle, or until timeoutMs has passed.
+ */
+fun HandlerThread.waitForIdle(timeoutMs: Int) = threadHandler.waitForIdle(timeoutMs.toLong())
+fun HandlerThread.waitForIdle(timeoutMs: Long) = threadHandler.waitForIdle(timeoutMs)
+fun Handler.waitForIdle(timeoutMs: Int) = waitForIdle(timeoutMs.toLong())
+fun Handler.waitForIdle(timeoutMs: Long) {
+    val cv = ConditionVariable(false)
+    post(cv::open)
+    if (!cv.block(timeoutMs)) {
+        fail("Handler did not become idle after ${timeoutMs}ms")
+    }
+}
+
+/**
+ * Block until the given Serial Executor becomes idle, or until timeoutMs has passed.
+ */
+fun waitForIdleSerialExecutor(executor: Executor, timeoutMs: Long) {
+    val cv = ConditionVariable()
+    executor.execute(cv::open)
+    if (!cv.block(timeoutMs)) {
+        fail("Executor did not become idle after ${timeoutMs}ms")
+    }
+}