Adding Skia Recorder to Render Engine

To start recording run:
adb shell setprop debug.renderengine.capture_skia_ms 1000

File will be stored in the /data directory on the device:
adb shell ls -al /data/user/
adb pull /data/user/re_skiacapture_<timestamp>.mskp

The recording will stop after MS specified. To reset the
recording, set the capture_skia_ms flag to a new time.
When recording is finished, the capture_skia_ms flag will
be set to 0 to avoid circular recording.

Bug: 173805658
Test: Turn on the flag. Turn off the flag. Pull the file from
      the device. Open it in Skia Debugger.
Change-Id: Iea478245c267fb4b26f980417d96acd7273bfb55
diff --git a/libs/renderengine/skia/debug/CommonPool.h b/libs/renderengine/skia/debug/CommonPool.h
new file mode 100644
index 0000000..7fc3d23
--- /dev/null
+++ b/libs/renderengine/skia/debug/CommonPool.h
@@ -0,0 +1,70 @@
+/*
+ * Copyright 2020 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.
+ */
+
+#pragma once
+
+#include <log/log.h>
+
+#include <condition_variable>
+#include <functional>
+#include <future>
+#include <mutex>
+#include <queue>
+
+namespace android {
+namespace renderengine {
+namespace skia {
+
+namespace {
+#define PREVENT_COPY_AND_ASSIGN(Type) \
+private:                              \
+    Type(const Type&) = delete;       \
+    void operator=(const Type&) = delete
+} // namespace
+
+/**
+ * Shamelessly copied from HWUI to execute Skia Capturing on the back thread in
+ * a safe manner.
+ */
+class CommonPool {
+    PREVENT_COPY_AND_ASSIGN(CommonPool);
+
+public:
+    using Task = std::function<void()>;
+    static constexpr auto THREAD_COUNT = 2;
+    static constexpr auto QUEUE_SIZE = 128;
+
+    static void post(Task&& func);
+
+private:
+    static CommonPool& instance();
+
+    CommonPool();
+    ~CommonPool() {}
+
+    void enqueue(Task&&);
+
+    void workerLoop();
+
+    std::mutex mLock;
+    std::condition_variable mCondition;
+    int mWaitingThreads = 0;
+    std::queue<Task> mWorkQueue;
+};
+
+} // namespace skia
+} // namespace renderengine
+} // namespace android