Load CMA backend from shared library

chromecast/public/task_runner.h

Index: chromecast/public/task_runner.h
diff --git a/chromecast/public/task_runner.h b/chromecast/public/task_runner.h
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+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROMECAST_PUBLIC_TASK_RUNNER_H_
+#define CHROMECAST_PUBLIC_TASK_RUNNER_H_
+
+#include <stdint.h>
+
+namespace chromecast {
+
+// Provides a way for vendor libraries to run code on a specific thread.
+// For example, cast_shell supplies an implementation of this interface through
+// media APIs (see MediaPipelineDeviceParams) to allow media backends to
+// schedule tasks to be run on the media thread.
+class TaskRunner {
+ public:
+  // Subclass and implement 'Run' to supply code to be run by PostTask or
+  // PostDelayedTask.  They both take ownership of the Task object passed in
+  // and will delete after running the Task.
+  class Task {
+   public:
+    virtual ~Task() {}
+    virtual void Run() = 0;
+  };
+
+  // Posts a task to the thread's task queue.  Delay of 0 could mean task
+  // runs immediately (within the call to PostTask, if it's called on the
+  // target thread) but there also could be some delay (the task could be added
+  // to target thread's task queue).
+  virtual bool PostTask(Task* task, uint64_t delay_milliseconds) = 0;
+
+ protected:
+  virtual ~TaskRunner() {}
+};
+
+}  // namespace chromecast
+
+#endif  // CHROMECAST_PUBLIC_TASK_RUNNER_H_