DialogSurfaceManager implementation.

media/base/android/dialog_surface_manager.h

+// 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_MANAGER_H_
+#define MEDIA_BASE_ANDROID_DIALOG_SURFACE_MANAGER_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/process/process_handle.h"
+#include "base/time/time.h"
+#include "media/base/android/dialog_surface.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 DialogSurfaceManager.
+// Typical usage is:
+//
+// callback = something that is a DialogSurface::Callback;
+// surface = DialogSurfaceManager::GetPointer()->CreateSurface(callback);

[Tima Vaisburd, 2016/08/03 18:05:13]

What is the type of |surface|? DialogSurface?

[liberato (no reviews please), 2016/08/03 23:11:55]

DialogSurface*, updated comment.

+// (wait for callback)
+// surface->GetSurface()

[Tima Vaisburd, 2016/08/03 18:05:13]

void Surface::GetSurface() on the surface object that already exists is
confusing to me. What does it really do?

[Tima Vaisburd, 2016/08/03 18:28:22]

After rereading the doc: I think in the doc CreateSurface(callback) was an async
call, did it become a sync (i.e. blocking) call? In the doc it was
  manager->RequestToCreateSurface(callback);
  <wait>
  Surface = manager->GetSurface();
which I understand.

Please note that the doc is neither referenced in this CL nor in the
corresponding bug, and it seems that we try to maintain the code to be
self-documented, so I guess it won't be referenced.

[liberato (no reviews please), 2016/08/03 23:11:55]

it returns the android surface.  probably clearer if i hadn't removed the
methods.  i put them back, commented out.

also open to other names -- i agree that GetSurface isn't descriptive.

[liberato (no reviews please), 2016/08/03 23:11:55]

not sure what you mean -- it's async here too.  in both cases, one must wait for
the callback to signal that the surface is created before expecting that
GetSurface will return non-null.

[Tima Vaisburd, 2016/08/04 00:21:09]

Ah, the DialogSurface is not a Surface...
So, as far as I get, it is a proxy object, like token, that you get at once, but
in invalid state; it later becomes valid, and then you can use it to get the
surface.

Can you send the token with the callback instead? E.g. DialogSurface::Callback
might take two parameters: Operation and DialogSurface* (I would rename to
something like SurfaceToken*). Then when you get it, it is already valid?

Alternatively, would a more traditional interface where DialogSurfaceManager
does all the job make sense in this situation? Its callback might return the
surface directly and layout can be changed with
   DialogSurfaceManager::ScheduleLayout(config, surface) ?
I do not know whether it would be better or not, it is just a question.

+// if (i_want_to_change_the_layout_)
+//   surface->ScheduleLayout(new_position_and_size);
+class MEDIA_EXPORT DialogSurfaceManager {
+ public:
+  // Return singleton manager instance.
+  static DialogSurfaceManager& Get();
+
+  using Config = DialogSurface::Config;
+
+  // Create a surface for renderer frame owned by renderer |pid|, and id
+  // |render_frame_id|.  May return null.
+  std::unique_ptr<DialogSurface> CreateSurface(
+      base::ProcessHandle pid,
+      int render_frame_id,
+      const Config& config,
+      const DialogSurface::Callback& cb);
+
+  static bool RegisterDialogSurfaceManager(JNIEnv* env);
+
+ protected:
+  DialogSurfaceManager();
+  ~DialogSurfaceManager();
+
+ private:
+  friend struct base::DefaultLazyInstanceTraits<DialogSurfaceManager>;
+
+  // Java DialogSurfaceManagerWrapper instance.
+  base::android::ScopedJavaGlobalRef<jobject> j_wrapped_manager_;
+
+  DISALLOW_COPY_AND_ASSIGN(DialogSurfaceManager);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_ANDROID_DIALOG_SURFACE_MANAGER_H_