Cache touch event's valuators at per touch level

Currently we cache touch event's valuator at per device level. It
means, if 2 fingers' valuators are updated together, these valuators
are mixed, e.g. if one drags one finger with small touch radius, and
another finger with big touch radius, we will see both fingers have
mixed small & big radius.

This CL changes valuator cache at per touch level.

BUG=159672
TEST=follow the test instruction in the issue and make sure it works.

Review URL: https://chromiumcodereview.appspot.com/19776012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@214829 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 8 insertions, 0 deletions

diff --git a/ui/base/events/event.cc b/ui/base/events/event.cc
index 4384d4a..0281310 100644
--- a/ui/base/events/event.cc
+++ b/ui/base/events/event.cc
@@ -491,6 +491,11 @@ TouchEvent::TouchEvent(EventType type,
 }
 
 TouchEvent::~TouchEvent() {
+  // In ctor TouchEvent(native_event) we call GetTouchId() which in X11
+  // platform setups the tracking_id to slot mapping. So in dtor here,
+  // if this touch event is a release event, we clear the mapping accordingly.
+  if (HasNativeEvent())
+    ClearTouchIdIfReleased(native_event());
 }
 
 void TouchEvent::Relocate(const gfx::Point& origin) {
diff --git a/ui/base/events/event_utils.h b/ui/base/events/event_utils.h
index aaa4a20..d57ced9 100644
--- a/ui/base/events/event_utils.h
+++ b/ui/base/events/event_utils.h
@@ -80,6 +80,9 @@ UI_EXPORT gfx::Vector2d GetMouseWheelOffset(
 // Gets the touch id from a native event.
 UI_EXPORT int GetTouchId(const base::NativeEvent& native_event);
 
+// Clear the touch id from bookkeeping if it is a release/cancel event.
+UI_EXPORT void ClearTouchIdIfReleased(const base::NativeEvent& native_event);
+
 // Gets the radius along the X/Y axis from a native event. Default is 1.0.
 UI_EXPORT float GetTouchRadiusX(const base::NativeEvent& native_event);
 UI_EXPORT float GetTouchRadiusY(const base::NativeEvent& native_event);