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
new file mode 100644
index 0000000000000000000000000000000000000000..2bfebf2aa04c120b87f310143f4fb16e17e111b8
--- /dev/null
+++ b/chromecast/public/task_runner.h
@@ -0,0 +1,38 @@
+// 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;
+  };
+
+  virtual ~TaskRunner() {}

[byungchul, 2015/07/30 17:19:06]

Should it be protected since it won't be destroyed by vendor?

[halliwell, 2015/07/30 18:20:18]

Done.

+
+  // 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;

[servolk, 2015/07/30 17:44:18]

We are using uint64_t values to represent number of microseconds in other parts
of public API (MediaComponentDevice), so maybe let's switch to microseconds here
as well for API consistency?

[halliwell, 2015/07/30 18:20:18]

Disagree, task posting has always been done in milliseconds and buffer
timestamps in microseconds.  Changing this would require lots of code changing
and risk of errors since there's no type checking, just numbers.

+};
+
+}  // namespace chromecast
+
+#endif  // CHROMECAST_PUBLIC_TASK_RUNNER_H_