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

third_party/WebKit/LayoutTests/http/tests/media/video-preload-cellular-test.js

+function load_video_base64(t, url, video) {
+  var request = new XMLHttpRequest();
+  request.open('GET', url, true);
+  request.responseType = 'arraybuffer';
+  request.onload = t.step_func(function(event) {
+    assert_equals(request.status, 200);
+    var bytes = new Uint8Array(request.response);
+    var binary = '';
+    for (var i = 0; i < bytes.byteLength; i++)
+      binary += String.fromCharCode(bytes[i]);
+    video.src = 'data:video/webm;base64,' + btoa(binary);
+  });
+  request.onerror = t.unreached_func();
+  request.send();
+}
+
+function cellular_preload_test(base64, preSrcExpected, postSrcExpected) {
+  async_test(function(t) {
+    internals.setNetworkStateNotifierTestOnly(true);
+    internals.setNetworkConnectionInfo('cellular', 2.0);
+
+    var video = document.querySelector('video');
+    assert_equals(video.preload, preSrcExpected);
+
+    var url = 'resources/media-source/webm/test.webm';
+    if (base64)
+      load_video_base64(t, url, video);
+    else
+      video.src = url;
+
+    video.onsuspend = t.step_func(function() {
+      assert_equals(video.preload, postSrcExpected);
+      t.done();
+    });
+
+    t.add_cleanup(function() {
+      internals.setNetworkStateNotifierTestOnly(false);
+    });
+  });
+}