Add perf tests for starting Chrome with URL

tools/telemetry/telemetry/page/actions/set_startup_url.py

Index: tools/telemetry/telemetry/page/actions/set_startup_url.py
diff --git a/tools/telemetry/telemetry/page/actions/javascript.py b/tools/telemetry/telemetry/page/actions/set_startup_url.py
similarity index 54%
copy from tools/telemetry/telemetry/page/actions/javascript.py
copy to tools/telemetry/telemetry/page/actions/set_startup_url.py
index 2edccefe1be070f572731be331328b803307f95c..f994292d324f8b307406c0aa05d1ecc3f9818e0d 100644
--- a/tools/telemetry/telemetry/page/actions/javascript.py
+++ b/tools/telemetry/telemetry/page/actions/set_startup_url.py
@@ -4,11 +4,11 @@
 
 from telemetry.page.actions import page_action
 
-
-class JavascriptAction(page_action.PageAction):
-  def __init__(self, attributes=None):
-    super(JavascriptAction, self).__init__(attributes)
+class SetStartupUrlAction(page_action.PageAction):

[jeremy, 2013/12/15 13:03:36]

Class comment plz

[aberent, 2013/12/16 17:07:43]

Done.

 
   def RunAction(self, page, tab, previous_action):
-    assert hasattr(self, 'expression')
-    tab.ExecuteJavaScript(self.expression)
+    pass
+
+  def CustomizeBrowserOptions(self, options):
+    assert hasattr(self,'startup_url')

[jeremy, 2013/12/15 13:03:36]

Also assert if this is a blank string?

[aberent, 2013/12/16 17:07:43]

My feeling is not. To get a blank string the JSON file would have to contain

"startup_url" : ""

and this doesn't seem particularly more likely than any other URL error.

In addition a blank string will actually work, and start the browser without a
URL, so this might make sense as a way of explicitly specifying that the test
doesn't want a startup URL, overriding anything on the benchmark's command line
or any default.

+    options.browser_options.startup_url = self.startup_url