power_LoadTest: Add parameter for custom tasks

client/site_tests/power_LoadTest/control

Index: client/site_tests/power_LoadTest/control
diff --git a/client/site_tests/power_LoadTest/control b/client/site_tests/power_LoadTest/control
index 4b05c1e0354f9836136de77be3c729e1ca4327de..3ef1245e87e7afb5d85ca8b83c7920668527fe72 100755
--- a/client/site_tests/power_LoadTest/control
+++ b/client/site_tests/power_LoadTest/control
@@ -32,5 +32,29 @@ import time
 loop_time = 3600
 loop_count = 11
 
+# To specify a list of custom tasks, pass in the task parameter:
+#    tasks='<task0> + <task1> + <task2> + ...'
+#
+# Task format:
+# - Open a window with some tabs, keep them open for some time:
+#       window;<comma-delimited urls>;<duration>
+# - Cycle through a list of sites one at a time, for a total duration, and a
+#   given delay on each site.
+#       cycle;<comma-delimited urls>;<duration>;<delay>
+#
+# Duration and delay are given in seconds.  The tasks are sequential.  So if
+# task0.duration=1800 and task1.duration=1200, task0 will run for 30 minutes,
+# followed by task1 for 20 minutes, for a total of 50 minutes.
+#
+# Example: Use the 'tasks' string below.  Pass 'tasks=tasks' as an argument into
+#          job.run_test().
+
+tasks='cycle;http://www.facebook.com,http://www.google.com,http://www.yahoo' + \
+      '.com;900;60 +' + \
+      'window;http://www.bing.com,http://www.gmail.com,http://www.amazon.co' + \
+      'm,http://www.ask.com;600 +' + \
+      'cycle;http://www.youtube.com,http://www.microsoft.com;900;240 +' + \
+      'window;http://www.wikipedia.org;1200'
+
 job.run_test('power_LoadTest', loop_time=loop_time, loop_count=loop_count,
               low_battery_threshold=3)