Adding support for diagonal scrolling to telemetry.

tools/telemetry/telemetry/page/actions/scroll_unittest.py

Index: tools/telemetry/telemetry/page/actions/scroll_unittest.py
diff --git a/tools/telemetry/telemetry/page/actions/scroll_unittest.py b/tools/telemetry/telemetry/page/actions/scroll_unittest.py
index 85b35f1c6800194e0d0d03a4d422d7bb5c298f7e..52450cb33024458c89309801d3d11bf1d20b1a26 100644
--- a/tools/telemetry/telemetry/page/actions/scroll_unittest.py
+++ b/tools/telemetry/telemetry/page/actions/scroll_unittest.py
@@ -10,7 +10,6 @@ from telemetry.unittest_util import tab_test_case
 
 
 class ScrollActionTest(tab_test_case.TabTestCase):
-  @decorators.Disabled  # Disabled due to flakiness: crbug.com/330544

[nednguyen, 2015/03/04 05:40:49]

Can you make a separate patch for enabling this? The less moving pieces in a
patch, the easier it's to keep track & revert if things go wrong.

   def testScrollAction(self):
     self.Navigate('blank.html')
 
@@ -47,6 +46,65 @@ class ScrollActionTest(tab_test_case.TabTestCase):
                     msg='scroll_position=%d; scroll_height=%d' %
                             (scroll_position, scroll_height))
 
+  def testDiagonalScrollAction(self):
+    self.Navigate('blank.html')
+
+    # Make page bigger than window so it's scrollable.
+    self._tab.ExecuteJavaScript("""document.body.style.height =
+                              (2 * window.innerHeight + 1) + 'px';""")
+    self._tab.ExecuteJavaScript("""document.body.style.width =
+                              (2 * window.innerWidth + 1) + 'px';""")
+
+    self.assertEquals(
+        self._tab.EvaluateJavaScript("""document.documentElement.scrollTop
+                                   || document.body.scrollTop"""), 0)
+    self.assertEquals(
+        self._tab.EvaluateJavaScript("""document.documentElement.scrollLeft
+                                   || document.body.scrollLeft"""), 0)
+
+    i = scroll.ScrollAction(direction='downright')
+    i.WillRunAction(self._tab)
+
+    self._tab.ExecuteJavaScript("""
+        window.__scrollAction.beginMeasuringHook = function() {
+            window.__didBeginMeasuring = true;
+        };
+        window.__scrollAction.endMeasuringHook = function() {
+            window.__didEndMeasuring = true;
+        };""")
+    i.RunAction(self._tab)
+
+    self.assertTrue(self._tab.EvaluateJavaScript('window.__didBeginMeasuring'))
+    self.assertTrue(self._tab.EvaluateJavaScript('window.__didEndMeasuring'))
+
+    # Allow for roundoff error in scaled viewport.
+    viewport_bottom = self._tab.EvaluateJavaScript(
+        """(document.documentElement.scrollTop || document.body.scrollTop)
+        + window.innerHeight""")
+    page_height = self._tab.EvaluateJavaScript('document.body.scrollHeight')
+    viewport_right = self._tab.EvaluateJavaScript(
+        """(document.documentElement.scrollLeft || document.body.scrollLeft)
+        + window.innerWidth""")
+    page_width = self._tab.EvaluateJavaScript('document.body.scrollWidth')
+
+    # The diagonal scrolling behaves like a square.
+    # It will not continue scrolling down if it cannot also scroll right.
+    # So determine which axis scrolled all the way to its end.
+    vertical_difference = abs(viewport_bottom - page_height)
+    horizontal_difference = abs(viewport_right - page_width)
+    scroll_distance = min(vertical_difference, horizontal_difference)
+    self.assertTrue(scroll_distance <= 1,
+                    msg=('vertical_difference=%d; '
+                         'horizontal_difference=%d; '
+                         'scroll_distance=%d '
+                         'page_height=%d '
+                         'page_width=%d') %
+                            (vertical_difference,
+                             horizontal_difference,
+                             scroll_distance,
+                             page_height,
+                             page_width))
+
   def testBoundingClientRect(self):
     self.Navigate('blank.html')