Monitor the intersection of video and viewport.

media/remoting/remoting_controller.cc

 // 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.
 
 #include "media/remoting/remoting_controller.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback_helpers.h"
 #include "base/logging.h"
@@ skipping 124 matching lines @@
   UpdateAndMaybeSwitch();
 }
 
 void RemotingController::OnExitedFullscreen() {
   DCHECK(task_runner_->BelongsToCurrentThread());
 
   is_fullscreen_ = false;
   UpdateAndMaybeSwitch();
 }
 
+void RemotingController::OnVideoViewportIntersectionChanged(
+    const ViewportIntersectionInfo& info) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+
+  // Reset on any notification, since this indicates the user is scrolling
+  // around in the document, the document is changing layout, etc.
+  viewport_fill_debouncer_timer_.Stop();
+
+  // Dropping below the threshold should instantly stop remote rendering.
+  if (info.ratio < 0.85) {
+    if (is_mostly_filling_viewport_) {
+      is_mostly_filling_viewport_ = false;
+      UpdateAndMaybeSwitch();
+    }
+    return;
+  }
+
+  // Meeting/Exceeding the threshold should hold steady for 5 seconds before
+  // starting remote rendering.
+  if (!is_mostly_filling_viewport_) {
+    viewport_fill_debouncer_timer_.Start(
+        FROM_HERE, base::TimeDelta::FromSeconds(5),
+        base::Bind(&RemotingController::OnViewportMostlyFilledAndUnchanging,
+                   weak_factory_.GetWeakPtr()));
+  }
+}
+
+void RemotingController::OnViewportMostlyFilledAndUnchanging() {
+  is_mostly_filling_viewport_ = true;
+  UpdateAndMaybeSwitch();
+}
+
 void RemotingController::OnSetCdm(CdmContext* cdm_context) {
   DCHECK(task_runner_->BelongsToCurrentThread());
 
   // TODO(xjz): Not implemented. Will add in up-coming change.
   NOTIMPLEMENTED();
 }
 
 void RemotingController::SetSwitchRendererCallback(
     const SwitchRendererCallback& cb) {
   DCHECK(task_runner_->BelongsToCurrentThread());
@@ skipping 70 matching lines @@
 
 bool RemotingController::ShouldBeRemoting() {
   DCHECK(task_runner_->BelongsToCurrentThread());
 
   // TODO(xjz): The control logic for EME will be added in a later CL.
   if (is_encrypted_)
     return false;
 
   if (!is_sink_available_)
     return false;
-  if (!is_fullscreen_)
-    return false;
   if (has_video_ && !IsVideoCodecSupported())
     return false;
   if (has_audio_ && !IsAudioCodecSupported())
     return false;
-  return true;
+  return is_fullscreen_ || is_mostly_filling_viewport_;
 }
 
 void RemotingController::UpdateAndMaybeSwitch() {
   DCHECK(task_runner_->BelongsToCurrentThread());
 
   // TODO(xjz): The switching logic for encrypted content will be added in a
   // later CL.
 
   // Demuxer is not initialized yet.
   if (!has_audio_ && !has_video_)
@@ skipping 11 matching lines @@
     // |swithc_renderer_cb_.Run()| will be called after remoting is started
     // successfully.
     remoter_->Start();
   } else {
     switch_renderer_cb_.Run();
     remoter_->Stop(mojom::RemotingStopReason::LOCAL_PLAYBACK);
   }
 }
 
 }  // namespace media