Merge 226767 "Do not transform scroll event ordinal values"

> Do not transform scroll event ordinal values
> 
> We don't need to transform scroll event ordinal values anymore as
> we now interpret them as DIPs across the whole stack. Otherwise,
> high-DPI devices (e.g. Pixel) would see the overscroll sensitivity
> downscaled by the device scale factor.
> 
> Contributed by sheckylin@chromium.org
> 
> BUG=300059
> TEST=Make sure it takes roughly the same distance to scroll on the
> touchpad to trigger the back/forward history navigation gesture on
> both Pixel and other low-res devices.
> 
> Review URL: https://codereview.chromium.org/25373005

TBR=sheckylin@chromium.org

Review URL: https://codereview.chromium.org/27520004

git-svn-id: svn://svn.chromium.org/chrome/branches/1650/src@228921 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 6 insertions, 22 deletions

diff --git a/ash/display/display_controller_unittest.cc b/ash/display/display_controller_unittest.cc
index 287b0e4..c2e3e7d 100644
--- a/ash/display/display_controller_unittest.cc
+++ b/ash/display/display_controller_unittest.cc
@@ -1148,11 +1148,11 @@ TEST_F(DisplayControllerTest, TouchScale) {
                            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_EQ(event_handler.scroll_x_offset(),
-            event_handler.scroll_x_offset_ordinal() * 2);
+            event_handler.scroll_x_offset_ordinal());
   EXPECT_EQ(event_handler.scroll_y_offset(),
-            event_handler.scroll_y_offset_ordinal() * 2);
+            event_handler.scroll_y_offset_ordinal());
 
   Shell::GetInstance()->RemovePreTargetHandler(&event_handler);
 }
diff --git a/ash/display/root_window_transformers_unittest.cc b/ash/display/root_window_transformers_unittest.cc
index d426a63..b300036 100644
--- a/ash/display/root_window_transformers_unittest.cc
+++ b/ash/display/root_window_transformers_unittest.cc
@@ -298,11 +298,11 @@ TEST_F(RootWindowTransformersTest, MAYBE_TouchScaleAndMagnify) {
                            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);
diff --git a/ui/events/event.cc b/ui/events/event.cc
index 46c31a6..7c3e6d5 100644
--- a/ui/events/event.cc
+++ b/ui/events/event.cc
@@ -741,18 +741,6 @@ void ScrollEvent::Scale(const float factor) {
   y_offset_ordinal_ *= factor;
 }
 
-void ScrollEvent::UpdateForRootTransform(
-    const gfx::Transform& inverted_root_transform) {
-  LocatedEvent::UpdateForRootTransform(inverted_root_transform);
-  gfx::DecomposedTransform decomp;
-  bool success = gfx::DecomposeTransform(&decomp, inverted_root_transform);
-  DCHECK(success);
-  if (decomp.scale[0])
-    x_offset_ordinal_ *= decomp.scale[0];
-  if (decomp.scale[1])
-    y_offset_ordinal_ *= decomp.scale[1];
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 // GestureEvent
 
diff --git a/ui/events/event.h b/ui/events/event.h
index 2a8c0df..358e3ee 100644
--- a/ui/events/event.h
+++ b/ui/events/event.h
@@ -656,10 +656,6 @@ class EVENTS_EXPORT ScrollEvent : public MouseEvent {
   float y_offset_ordinal() const { return y_offset_ordinal_; }
   int finger_count() const { return finger_count_; }
 
-  // Overridden from LocatedEvent.
-  virtual void UpdateForRootTransform(
-      const gfx::Transform& inverted_root_transform) OVERRIDE;
-
  private:
   // Potential accelerated offsets.
   float x_offset_;