Do not transform scroll event ordinal values

ash/display/root_window_transformers_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/display/root_window_transformers.h"
 
 #include "ash/display/display_controller.h"
 #include "ash/display/display_info.h"
 #include "ash/display/display_manager.h"
 #include "ash/launcher/launcher.h"
@@ skipping 280 matching lines @@
   generator.PressMoveAndReleaseTouchTo(50, 50);
   // Default test touches have radius_x/y = 1.0, with device scale
   // factor = 2, the scaled radius_x/y should be 0.5.
   EXPECT_FLOAT_EQ(0.2f, event_handler.touch_radius_x());
   EXPECT_FLOAT_EQ(0.2f, event_handler.touch_radius_y());
 
   generator.ScrollSequence(gfx::Point(0,0),
                            base::TimeDelta::FromMilliseconds(100),
                            10.0, 1.0, 5, 1);
 
-  // With device scale factor = 2, ordinal_offset * 2 = offset.
+  // ordinal_offset is invariant to the device scale factor.
   EXPECT_FLOAT_EQ(event_handler.scroll_x_offset(),
-                  event_handler.scroll_x_offset_ordinal() * 2 * 2.5f);
+                  event_handler.scroll_x_offset_ordinal());
   EXPECT_FLOAT_EQ(event_handler.scroll_y_offset(),
-                  event_handler.scroll_y_offset_ordinal() * 2 * 2.5f);
+                  event_handler.scroll_y_offset_ordinal());
   magnifier->SetEnabled(false);
 
   Shell::GetInstance()->RemovePreTargetHandler(&event_handler);
 }
 
 TEST_F(RootWindowTransformersTest, MAYBE_ConvertHostToRootCoords) {
   TestEventHandler event_handler;
   Shell::GetInstance()->AddPreTargetHandler(&event_handler);
   MagnificationController* magnifier =
       Shell::GetInstance()->magnification_controller();
@@ skipping 91 matching lines @@
   EXPECT_EQ("0,125,0,125", transformer->GetHostInsets().ToString());
 
   UpdateDisplay("200x400,500x500");
   // The aspect ratio is flipped, so X margin is now 125.
   transformer = test_api.CreateCurrentRootWindowTransformer();
   EXPECT_EQ("125,0,125,0", transformer->GetHostInsets().ToString());
 }
 
 }  // namespace test
 }  // namespace ash