6 files changed, 43 insertions, 0 deletions
diff --git a/ui/base/touch/touch_device.cc b/ui/base/touch/touch_device.cc
index de7785c..944ba17 100644
--- a/ui/base/touch/touch_device.cc
+++ b/ui/base/touch/touch_device.cc
@@ -12,4 +12,8 @@ bool IsTouchDevicePresent() {
   return false;
 }
 
+int MaxTouchPoints() {
+  return 0;
+}
+
 }  // namespace ui
diff --git a/ui/base/touch/touch_device.h b/ui/base/touch/touch_device.h
index 8cc4b7d..b06c564 100644
--- a/ui/base/touch/touch_device.h
+++ b/ui/base/touch/touch_device.h
@@ -9,9 +9,23 @@
 
 namespace ui {
 
+// TODO(sblom): This is non-standard, and should be removed before
+// RuntimeEnabledFlags::PointerEventsMaxTouchPoints is marked stable.
+// Tracked by: http://crbug.com/308649
+const int kMaxTouchPointsUnknown = -1;
+
 // Returns true if a touch device is available.
 UI_EXPORT bool IsTouchDevicePresent();
 
+// Returns the maximum number of simultaneous touch contacts supported
+// by the device. In the case of devices with multiple digitizers (e.g.
+// multiple touchscreens), the value MUST be the maximum of the set of
+// maximum supported contacts by each individual digitizer.
+// For example, suppose a device has 3 touchscreens, which support 2, 5,
+// and 10 simultaneous touch contacts, respectively. This returns 10.
+// http://www.w3.org/TR/pointerevents/#widl-Navigator-maxTouchPoints
+UI_EXPORT int MaxTouchPoints();
+
 }  // namespace ui
 
 #endif  // UI_BASE_TOUCH_TOUCH_DEVICE_H_
diff --git a/ui/base/touch/touch_device_android.cc b/ui/base/touch/touch_device_android.cc
index 39e34c2..2b359c0 100644
--- a/ui/base/touch/touch_device_android.cc
+++ b/ui/base/touch/touch_device_android.cc
@@ -10,4 +10,17 @@ bool IsTouchDevicePresent() {
   return true;
 }
 
+// Looks like the best we can do here is detect 1, 2+, or 5+ by
+// feature detecting:
+// FEATURE_TOUCHSCREEN (1),
+// FEATURE_TOUCHSCREEN_MULTITOUCH (2),
+// FEATURE_TOUCHSCREEN_MULTITOUCH_DISTINCT (2+), or
+// FEATURE_TOUCHSCREEN_MULTITOUCH_JAZZHANDS (5+)
+//
+// Probably start from the biggest and detect down the list until we
+// find one that's supported and return its value.
+int MaxTouchPoints() {
+  return kMaxTouchPointsUnknown;
+}
+
 }  // namespace ui
diff --git a/ui/base/touch/touch_device_aurax11.cc b/ui/base/touch/touch_device_aurax11.cc
index 04d435e..d3b6df4 100644
--- a/ui/base/touch/touch_device_aurax11.cc
+++ b/ui/base/touch/touch_device_aurax11.cc
@@ -11,4 +11,8 @@ bool IsTouchDevicePresent() {
   return ui::TouchFactory::GetInstance()->IsTouchDevicePresent();
 }
 
+int MaxTouchPoints() {
+  return kMaxTouchPointsUnknown;
+}
+
 }  // namespace ui
diff --git a/ui/base/touch/touch_device_ozone.cc b/ui/base/touch/touch_device_ozone.cc
index 7cb2ecb..d97a70b 100644
--- a/ui/base/touch/touch_device_ozone.cc
+++ b/ui/base/touch/touch_device_ozone.cc
@@ -11,4 +11,8 @@ bool IsTouchDevicePresent() {
   return true;
 }
 
+int MaxTouchPoints() {
+  return kMaxTouchPointsUnknown;
+}
+
 }  // namespace ui
diff --git a/ui/base/touch/touch_device_win.cc b/ui/base/touch/touch_device_win.cc
index c07fbe9..ba5c260 100644
--- a/ui/base/touch/touch_device_win.cc
+++ b/ui/base/touch/touch_device_win.cc
@@ -14,4 +14,8 @@ bool IsTouchDevicePresent() {
       ((value & NID_INTEGRATED_TOUCH) || (value & NID_EXTERNAL_TOUCH));
 }
 
+int MaxTouchPoints() {
+  return GetSystemMetrics(SM_MAXIMUMTOUCHES);
+}
+
 }  // namespace ui