Add AndroidVideoSurfaceChooser to manage overlays.

media/gpu/avda_overlay_helper_impl.cc

+// Copyright 2017 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.
+
+#include "media/gpu/avda_overlay_helper_impl.h"
+
+namespace media {
+
+AVDAOverlayHelperImpl::AVDAOverlayHelperImpl() : weak_factory_(this) {}
+
+AVDAOverlayHelperImpl::~AVDAOverlayHelperImpl() {}
+
+void AVDAOverlayHelperImpl::Startup(
+    const UseOverlayCB& use_overlay_cb,
+    const UseSurfaceTextureCB& use_surface_texture_cb,
+    const StopUsingOverlayImmediatelyCB& stop_immediately_cb,
+    std::unique_ptr<AndroidOverlayFactory> initial_factory) {
+  use_overlay_cb_ = use_overlay_cb;
+  use_surface_texture_cb_ = use_surface_texture_cb;
+  stop_immediately_cb_ = stop_immediately_cb;
+
+  if (initial_factory) {
+    // We requested an overlay.  Wait to see if it succeeds or fails, since
+    // hopefully this will be fast.  On M+, we could ask it to start with a
+    // SurfaceTexture either way.  Before M, we can't switch surfaces.  In that
+    // case, it's important not to request a SurfaceTexture if we have an
+    // overlay pending, so that we know not to transition to SurfaceTexture.
+    client_notification_pending_ = true;
+    OnOverlayFactory(std::move(initial_factory));
+  }
+
+  if (!overlay_) {
+    // We haven't requested an overlay yet.  Just ask the client to start with
+    // SurfaceTexture now.
+    use_surface_texture_cb_.Run();
+    return;
+  }
+}
+
+void AVDAOverlayHelperImpl::OnOverlayFactory(
+    std::unique_ptr<AndroidOverlayFactory> factory) {
+  // If we have an overlay, then we should transition away from it.  It
+  // doesn't matter if we have a new factory or no factory; the old overlay goes
+  // with the old factory.
+
+  // Notify the client to transition to SurfaceTexture, which it might already
+  // be using.  If |!client_notification_pending_|, then we're still during
+  // initial startup, so we don't switch the client.  Otherwise, we'd cause
+  // pre-M to break, since we'd start with a SurfaceTexture in all cases.
+  // TODO(liberato): should we switch immediately away, at least for CVV, if
+  // |!factory|?  It means that we're probably leaving full screen.
+  // We don't do this just to match previous behavior, which always went through
+  // AVDA::SetSurface, which was the slower transition.  However, the CVV
+  // won't be visible soon, so maybe that's the wrong thing to do.  For DS,

[tguilbert, 2017/04/21 22:55:46]

DS is not clear in this context. Can you use the un-abbreviated form?

[liberato (no reviews please), 2017/04/27 18:30:12]

Done.

+  // it would be fine to transition slower to avoid dropping frames.  Note
+  // that we'd have to not only remember the most recent overlay that we sent
+  // to the client, but we'd also have to find out when the client drops it.
+  // We'd have a raw ptr only, which might be re-used.
+  if (!client_notification_pending_)
+    use_surface_texture_cb_.Run();
+
+  // If we started construction of an overlay, but it's not ready yet, then
+  // just drop it.
+  if (overlay_)
+    overlay_ = nullptr;
+
+  overlay_factory_ = std::move(factory);
+
+  // If we don't have a new factory, then just stop here.
+  if (!overlay_factory_)
+    return;
+
+  // We just got an overlay factory.  Get an overlay immediately.  This is
+  // the right behavior to match what AVDA does with CVV.  For DS, we should
+  // probably check to see if it's a good idea, at least on M+.
+  // Also note that for pre-M, AVDA depends on this behavior, else it will get
+  // a SurfaceTexture then be unable to switch.  Perhaps there should be a
+  // pre-M implementation of this class that guarantees that it won't change
+  // between the two.
+  AndroidOverlay::Config config;
+  // We bind all of our callbacks with weak ptrs, since we don't know how long
+  // the client will hold on to overlays.  They could, in principle, show up
+  // long after the client is destroyed too, if codec destruction hangs.
+  config.ready_cb = base::Bind(&AVDAOverlayHelperImpl::OnOverlayReady,
+                               weak_factory_.GetWeakPtr());
+  config.failed_cb = base::Bind(&AVDAOverlayHelperImpl::OnOverlayFailed,
+                                weak_factory_.GetWeakPtr());
+  config.destroyed_cb = base::Bind(&AVDAOverlayHelperImpl::OnSurfaceDestroyed,
+                                   weak_factory_.GetWeakPtr());
+  // TODO(liberato): where do we get the initial size from?  For CVV, it's
+  // set via the natural size, and this is ignored anyway.  The client should
+  // provide this.
+  config.rect = gfx::Rect(0, 0, 1, 1);
+  overlay_ = overlay_factory_->CreateOverlay(config);
+}
+
+void AVDAOverlayHelperImpl::OnOverlayReady(AndroidOverlay* overlay) {
+  // We |overlay_| is the only overlay for which we haven't gotten a ready
+  // callback yet.
+  DCHECK_EQ(overlay, overlay_.get());
+
+  // If we haven't sent the client notification yet, we're doing so now.
+  client_notification_pending_ = false;
+
+  use_overlay_cb_.Run(std::move(overlay_));
+}
+
+void AVDAOverlayHelperImpl::OnOverlayFailed(AndroidOverlay* overlay) {
+  // We shouldn't get a failure for any overlay except the incoming one.
+  DCHECK_EQ(overlay, overlay_.get());
+
+  // If we owe the client a notification callback, then send it.
+  if (client_notification_pending_) {
+    // The overlay that we requested failed, so notify the client to try
+    // using SurfaceTexture instead.
+    client_notification_pending_ = false;
+    use_surface_texture_cb_.Run();
+  }
+
+  overlay_ = nullptr;
+}
+
+void AVDAOverlayHelperImpl::OnSurfaceDestroyed(AndroidOverlay* overlay) {
+  // We shouldn't get OnSurfaceDestroyed unless we previously got Ready.  In
+  // that case, we should have notified the client then.
+  DCHECK(!client_notification_pending_);
+
+  // We should not get OnSurfaceDestroyed for the incoming overlay, since we
+  // should't get OnSurfaceDestroyed before OnSurfaceReady.  OnSurfaceReady
+  // should imply that this isn't the incoming overlay.
+  DCHECK_NE(overlay_.get(), overlay);
+
+  // We unconditionally send 'stop immediately', since we don't know what
+  // overlay this is.  Even if we revoked the overlay before, we may have done
+  // so with the slow transition, which isn't good enough now.  The client has
+  // to be smart enoug to understand if it's currently using |overlay| or not.
+
+  // Also remember that we don't know when the client drops the overlay, after
+  // we revoke it.  We can get callbacks until that happens, even if (for
+  // example), the overlay is waiting for MediaCodec destruction.  So, it's
+  // likely that we'll send callbacks for overlays that the client is already
+  // not using.
+  stop_immediately_cb_.Run(overlay);
+}
+
+}  // namespace media