Only force preload=none over cellular for http, https, ftp URLs.

third_party/WebKit/Source/core/html/HTMLMediaElement.cpp

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 990 matching lines @@
             }
         }
     }
 
     if (attemptLoad && canLoadURL(url, contentType)) {
         ASSERT(!webMediaPlayer());
 
         if (effectivePreloadType() == WebMediaPlayer::PreloadNone) {
             WTF_LOG(Media, "HTMLMediaElement::loadResource(%p) : Delaying load because preload == 'none'", this);
             deferLoad();
+        } else if (networkStateNotifier().isCellularConnectionType() && (m_currentSrc.protocolIsInHTTPFamily() || m_currentSrc.protocolIs("ftp"))) {

[philipj_slow, 2016/03/21 11:59:37]

OK, so since we last discussed this, srirama@ has done some refactoring so that
effectivePreloadType() is now the single source of truth for preload. So you
should be able to simply move these bits into effectivePreloadType(), which
would also make it very clear how it interacts with autoplay and the
m_ignorePreloadNone state. (I assume that preload should not matter, but that
m_ignorePreloadNone should take precedent, so some reshuffling will be needed.)

If the log message is important, maybe effectivePreloadType() could take an
extra out argument to say why preload was none. Seems like overkill, though.

+            WTF_LOG(Media, "HTMLMediaElement::loadResource(%p) : Delaying load because because of cellular network.", this);
+            deferLoad();
         } else {
             startPlayerLoad();
         }
     } else {
         mediaLoadingFailed(WebMediaPlayer::NetworkStateFormatError);
     }
 
     // If there is no poster to display, allow the media engine to render video frames as soon as
     // they are available.
     updateDisplayState();
@@ skipping 895 matching lines @@
 }
 
 void HTMLMediaElement::setPreload(const AtomicString& preload)
 {
     WTF_LOG(Media, "HTMLMediaElement::setPreload(%p, %s)", this, preload.utf8().data());
     setAttribute(preloadAttr, preload);
 }
 
 WebMediaPlayer::Preload HTMLMediaElement::preloadType() const
 {
-    // Force preload to none for cellular connections.
-    if (networkStateNotifier().isCellularConnectionType()) {
-        UseCounter::count(document(), UseCounter::HTMLMediaElementPreloadForcedNone);
-        return WebMediaPlayer::PreloadNone;
-    }
-
     const AtomicString& preload = fastGetAttribute(preloadAttr);
     if (equalIgnoringCase(preload, "none")) {
         UseCounter::count(document(), UseCounter::HTMLMediaElementPreloadNone);
         return WebMediaPlayer::PreloadNone;
     }
     if (equalIgnoringCase(preload, "metadata")) {
         UseCounter::count(document(), UseCounter::HTMLMediaElementPreloadMetadata);
         return WebMediaPlayer::PreloadMetaData;
     }
     if (equalIgnoringCase(preload, "auto")) {
@@ skipping 1869 matching lines @@
 {
     visitor->trace(m_client);
 }
 
 DEFINE_TRACE(HTMLMediaElement::AudioSourceProviderImpl)
 {
     visitor->trace(m_client);
 }
 
 } // namespace blink