Adding tests for diagonal scrolling in telemetry.

tools/telemetry/telemetry/page/actions/scroll.py

Index: tools/telemetry/telemetry/page/actions/scroll.py
diff --git a/tools/telemetry/telemetry/page/actions/scroll.py b/tools/telemetry/telemetry/page/actions/scroll.py
index ab80058f9688051f86417a0d104fe61931e8368b..61f2fc8673826035e38ee21a55985ea82cbac1a5 100644
--- a/tools/telemetry/telemetry/page/actions/scroll.py
+++ b/tools/telemetry/telemetry/page/actions/scroll.py
@@ -14,7 +14,9 @@ class ScrollAction(page_action.PageAction):
                distance=None, distance_expr=None,
                speed_in_pixels_per_second=800, use_touch=False):
     super(ScrollAction, self).__init__()
-    if direction not in ['down', 'up', 'left', 'right']:
+    if direction not in ['down', 'up', 'left', 'right',
+                         'downleft', 'downright',
+                         'upleft', 'upright']:

[nednguyen, 2015/03/16 16:52:40]

Can you add a check of chrome branch number here and throw ValueException if the
diagonal actions are not supported?
You also want to add a TODO to remove the check once the chrome stable passes
that branch.

[cblume, 2015/03/26 00:15:05]

Ideally, right here in the constructor is where the ValueError would be thrown.
However, from the constructor I don't seem to have a good way to check the
Chrome branch number.

I can check from within WillRunAction or RunAction, since those are provided a
tab object. What do you think?

       raise page_action.PageActionNotSupported(
           'Invalid scroll direction: %s' % self.direction)
     self._selector = selector