Defer media loading while on cellular networks.

third_party/WebKit/Source/core/page/NetworkStateNotifier.h

 /*
  * Copyright (C) 2008 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 72 matching lines @@
     // before its ExecutionContext is deleted. It's possible for an observer to
     // be called twice for the same event if it is first removed and then added
     // during notification.
     void addObserver(NetworkStateObserver*, ExecutionContext*);
     void removeObserver(NetworkStateObserver*, ExecutionContext*);
 
     // The following functions are for testing purposes.
 
     // When true, setWebConnectionType calls are ignored and only setWebConnectionTypeForTest
     // can update the connection type. This is used for layout tests (see crbug.com/377736).
+    //
+    // Since this class is a singleton, tests must call this with false when completed to
+    // avoid indeterminate state across the test harness. When switching in or out of test
+    // mode, all state will be reset to default values.
     void setTestUpdatesOnly(bool);
     // Tests should call this as it will change the type regardless of the value of m_testUpdatesOnly.
     void setWebConnectionForTest(WebConnectionType, double maxBandwidthMbps);
 
 private:
     struct ObserverList {
         ObserverList()
             : iterating(false)
         {
         }
@@ skipping 22 matching lines @@
     double m_maxBandwidthMbps;
     ObserverListMap m_observers;
     bool m_testUpdatesOnly;
 };
 
 CORE_EXPORT NetworkStateNotifier& networkStateNotifier();
 
 } // namespace blink
 
 #endif // NetworkStateNotifier_h