events: Make sure the unaccelerated scroll deltas get adjusted properly for device-scale-factor.

BUG=none

Review URL: https://codereview.chromium.org/12321090/
Review URL: https://codereview.chromium.org/12391022

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@185346 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 15 insertions, 0 deletions

diff --git a/ui/base/events/event.cc b/ui/base/events/event.cc
index 079e5f7..ad26a24 100644
--- a/ui/base/events/event.cc
+++ b/ui/base/events/event.cc
@@ -679,6 +679,17 @@ void ScrollEvent::Scale(const float factor) {
   y_offset_ordinal_ *= factor;
 }
 
+void ScrollEvent::UpdateForRootTransform(const gfx::Transform& root_transform) {
+  LocatedEvent::UpdateForRootTransform(root_transform);
+  gfx::DecomposedTransform decomp;
+  bool success = gfx::DecomposeTransform(&decomp, 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/base/events/event.h b/ui/base/events/event.h
index a50823a..95e34ce 100644
--- a/ui/base/events/event.h
+++ b/ui/base/events/event.h
@@ -655,6 +655,10 @@ class UI_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& root_transform) OVERRIDE;
+
  private:
   // Potential accelerated offsets.
   float x_offset_;