smoothness.scrolling_tough_ad_cases to use browser driven scrolls

tools/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend.py

Index: tools/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend.py
diff --git a/tools/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend.py b/tools/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend.py
index 3aa050a1f6f31bf9186167fe66fbde5f5e373fc5..e1e3e0a0b9e268a3c8bef62436cac7dadb3e17f2 100644
--- a/tools/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend.py
+++ b/tools/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend.py
@@ -223,6 +223,65 @@ class InspectorBackend(object):
     """
     return self._runtime.EnableAllContexts()
 
+  @_HandleInspectorWebSocketExceptions
+  def SynthesizeScrollGesture(self, x=100, y=800, xDistance=0, yDistance=-500,
+                              xOverscroll=None, yOverscroll=None,
+                              preventFling=True, speed=None,
+                              gestureSourceType=None, repeatCount=None,
+                              repeatDelayMs=None, interactionMarkerName=None,
+                              timeout=60):
+    """Runs an inspector command that causes a repeatable browser driven scroll.
+
+    Args:
+      x: X coordinate of the start of the gesture in CSS pixels.
+      y: Y coordinate of the start of the gesture in CSS pixels.
+      xDistance: Distance to scroll along the X axis (positive to scroll left).
+      yDistance: Distance to scroll along the Y axis (positive to scroll up).
+      xOverscroll: Number of additional pixels to scroll back along the X axis.
+      xOverscroll: Number of additional pixels to scroll back along the Y axis.
+      preventFling: Prevents a fling gesture.
+      speed: Swipe speed in pixels per second.
+      gestureSourceType: Which type of input events to be generated.
+      repeatCount: Number of additional repeats beyond the first scroll.
+      repeatDelayMs: Number of milliseconds delay between each repeat.
+      interactionMarkerName: The name of the interaction markers to generate.
+
+    Raises:
+      exceptions.TimeoutException
+      exceptions.DevtoolsTargetCrashException
+    """
+    params = {
+        'x': x,
+        'y': y,
+        'xDistance': xDistance,
+        'yDistance': yDistance,
+        'preventFling': preventFling,
+    }
+
+    if xOverscroll is not None:
+      params['xOverscroll'] = xOverscroll
+
+    if yOverscroll is not None:
+      params['yOverscroll'] = yOverscroll
+
+    if speed is not None:
+      params['speed'] = speed
+
+    if repeatCount is not None:
+      params['repeatCount'] = repeatCount
+
+    if repeatDelayMs is not None:
+      params['repeatDelayMs'] = repeatDelayMs
+
+    if interactionMarkerName is not None:
+      params['interactionMarkerName'] = interactionMarkerName
+
+    scroll_command = {
+      'method': 'Input.synthesizeScrollGesture',
+      'params': params
+    }
+    return self._runtime.RunInspectorCommand(scroll_command, timeout)
+
   # Timeline public methods.
 
   @property