chrome/common/extensions/docs/templates/intros/power.html

   1 <h2 id="usage">Usage</h2>
   2
   3 <p>
   4 By default,
   5 operating systems dim the screen when users are inactive
   6 and eventually suspend the system.
   7 With the power API,
   8 an app or extension can keep the system awake.
   9 </p>
  10
  11 <p>
  12 Using this API,
  13 you can specify the
  14 $ref:Level to which power management is disabled.
  15 The <code>"system"</code> level keeps the system active,
  16 but allows the screen to be dimmed or turned off.
  17 For example,
  18 a communication app can continue to receive messages
  19 while the screen is off.
  20 The <code>"display"</code> level keeps the screen and system active.
  21 E-book and presentation apps, for example,
  22 can keep the screen and system active
  23 while users read.
  24 </p>
  25
  26 <p>
  27 When a user has more than one app or extension active,
  28 each with its own power level,
  29 the highest-precedence level takes effect;
  30 <code>"display"</code> always takes precendence
  31 over <code>"system"</code>.
  32 For example,
  33 if app A asks for <code>"system"</code> power management,
  34 and app B asks for <code>"display"</code>,
  35 <code>"display"</code> is used until app B
  36 is unloaded or releases its request.
  37 If app A is still active,
  38 <code>"system"</code> is then used.
  39 </p>