Defer media loading while on cellular networks.

third_party/WebKit/LayoutTests/netinfo/resources/netinfo_common.js

Index: third_party/WebKit/LayoutTests/netinfo/resources/netinfo_common.js
diff --git a/third_party/WebKit/LayoutTests/netinfo/resources/netinfo_common.js b/third_party/WebKit/LayoutTests/netinfo/resources/netinfo_common.js
index 57e3c45dbb900469f8e26a8143963197d5680536..49562951fdadbf566d9415b65f6d026611d6ff5c 100644
--- a/third_party/WebKit/LayoutTests/netinfo/resources/netinfo_common.js
+++ b/third_party/WebKit/LayoutTests/netinfo/resources/netinfo_common.js
@@ -10,5 +10,10 @@ var newDownlinkMax = 2.0;
 if (window.internals) {
     internals.setNetworkStateNotifierTestOnly(true);
     internals.setNetworkConnectionInfo(initialType, initialDownlinkMax);
+
+    // Reset the state of the singleton network state notifier.

[philipj_slow, 2015/10/01 09:24:07]

Is this needed to prevent some other tests from failing? Would the
t.add_cleanup() construct make this redundant?

[DaleCurtis, 2015/10/01 19:25:54]

No, it's not causing any failures, but w/o it the tests may have ordering
dependencies since the settings of one will carry over into the other.

+    window.onbeforeunload = function() {
+        internals.setNetworkStateNotifierTestOnly(false);
+    }
 }