DialogSurfaceHolder implementation.

media/base/android/dialog_surface_callback.h

Index: media/base/android/dialog_surface_callback.h
diff --git a/media/base/android/dialog_surface_callback.h b/media/base/android/dialog_surface_callback.h
new file mode 100644
index 0000000000000000000000000000000000000000..ab132e1c55e05172a3dccd37167c36e94deddd8c
--- /dev/null
+++ b/media/base/android/dialog_surface_callback.h
@@ -0,0 +1,79 @@
+// Copyright 2016 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 MEDIA_BASE_ANDROID_DIALOG_SURFACE_CALLBACK_H_
+#define MEDIA_BASE_ANDROID_DIALOG_SURFACE_CALLBACK_H_
+
+#include <jni.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include <set>
+#include <string>
+
+#include "base/android/scoped_java_ref.h"
+#include "base/lazy_instance.h"
+#include "base/macros.h"
+#include "base/single_thread_task_runner.h"
+#include "base/task_runner.h"
+#include "base/threading/thread_checker.h"
+#include "base/time/time.h"
+#include "media/base/android/dialog_surface_holder.h"
+#include "media/base/media_export.h"
+#include "ui/gfx/geometry/point.h"
+#include "ui/gfx/geometry/size.h"
+
+namespace media {
+
+// This class implements the C++ wrapper around the java DialogSurfaceCallback.
+// It handles threading and object lifecycle issues.
+class MEDIA_EXPORT DialogSurfaceCallback {
+ public:
+  // |callback| will be called on the same thread that we're created on,
+  // regardless of the thread that's used to call from java.
+  DialogSurfaceCallback(const DialogSurfaceHolder::Callback& callback);
+  ~DialogSurfaceCallback();
+
+  scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner() const;
+  bool CalledOnValidThread() const;
+
+  jobject obj() const { return j_surface_callback_.obj(); }
+
+  // Called on the proper thread for the callback for |id|, though |id| might
+  // no longer refer to a valid callback.
+  static void OnCallbackProperThread(long id,
+                                     DialogSurfaceHolder::CallbackOp what,
+                                     base::WaitableEvent* event);
+
+  // Process a callback from java.
+  // It would be nice if this didn't have to be static, but the multi-threaded
+  // nature of DialogSurface makes it very hard to do safely.
+  // This may be called on any thread.
+  static void OnCallback(JNIEnv* env,
+                         const base::android::JavaParamRef<jobject>& obj,
+                         long id,
+                         int what);
+
+  static bool RegisterDialogSurfaceCallback(JNIEnv* env);
+
+ private:
+  // Java callback instance.
+  base::android::ScopedJavaGlobalRef<jobject> j_surface_callback_;
+
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+
+  // |id_| must be non-repeating.  We can't use |this| directly because of race
+  // conditions with destruction and re-allocation.
+  long id_;
+
+  DialogSurfaceHolder::Callback callback_;
+
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(DialogSurfaceCallback);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_ANDROID_DIALOG_SURFACE_CALLBACK_H_