Detect change on the intersection of video and viewport.

third_party/WebKit/Source/web/FrameLoaderClientImpl.cpp

 /*
  * Copyright (C) 2009, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 757 matching lines @@
     WebMediaPlayerClient* client) {
   WebLocalFrameImpl* webFrame =
       WebLocalFrameImpl::fromFrame(htmlMediaElement.document().frame());
 
   if (!webFrame || !webFrame->client())
     return nullptr;
 
   HTMLMediaElementEncryptedMedia& encryptedMedia =
       HTMLMediaElementEncryptedMedia::from(htmlMediaElement);
   WebString sinkId(HTMLMediaElementAudioOutputDevice::sinkId(htmlMediaElement));
-  return wrapUnique(webFrame->client()->createMediaPlayer(
-      source, client, &encryptedMedia, encryptedMedia.contentDecryptionModule(),
-      sinkId));
+
+  std::unique_ptr<WebMediaPlayer> mediaPlayer =
+      wrapUnique(webFrame->client()->createMediaPlayer(
+          source, client, &encryptedMedia,
+          encryptedMedia.contentDecryptionModule(), sinkId));
+  WebMediaPlayer::ViewportIntersectionInfo intersectInfo =

[miu, 2016/11/22 00:14:30]

nit: Is this local variable (intersectInfo) needed? You can eliminate a copy of
the struct by:

  mediaPlayer->viewportIntersectionChanged(
      htmlMediaElement.currentViewportIntersection());

[xjz, 2016/11/23 23:43:25]

Not applicable. I find that we don't need make change here. Instead, this can be
done in HTMLMediaElement.

+      htmlMediaElement.currentViewportIntersection();
+  mediaPlayer->viewportIntersectionChanged(intersectInfo);
+  return mediaPlayer;
 }
 
 WebRemotePlaybackClient* FrameLoaderClientImpl::createWebRemotePlaybackClient(
     HTMLMediaElement& htmlMediaElement) {
   return HTMLMediaElementRemotePlayback::remote(htmlMediaElement);
 }
 
 ObjectContentType FrameLoaderClientImpl::getObjectContentType(
     const KURL& url,
     const String& explicitMimeType,
@@ skipping 193 matching lines @@
 WebDevToolsAgentImpl* FrameLoaderClientImpl::devToolsAgent() {
   return WebLocalFrameImpl::fromFrame(m_webFrame->frame()->localFrameRoot())
       ->devToolsAgentImpl();
 }
 
 KURL FrameLoaderClientImpl::overrideFlashEmbedWithHTML(const KURL& url) {
   return m_webFrame->client()->overrideFlashEmbedWithHTML(WebURL(url));
 }
 
 }  // namespace blink