Make Interaction Media Features MQ dynamic on Linux.

ui/base/touch/touch_device_linux.cc

Index: ui/base/touch/touch_device_linux.cc
diff --git a/ui/base/touch/touch_device_linux.cc b/ui/base/touch/touch_device_linux.cc
index 3ebf53c3a2fda51106671eeaa8e86a7a1fd3ff4d..d9ef84f2e6f6d4a56b1a8af7385210cfa281dd84 100644
--- a/ui/base/touch/touch_device_linux.cc
+++ b/ui/base/touch/touch_device_linux.cc
@@ -15,27 +15,44 @@ bool IsTouchDevicePresent() {
   return !InputDeviceManager::GetInstance()->GetTouchscreenDevices().empty();
 }
 
-// TODO(mustaq@chromium.org): Use mouse detection logic. crbug.com/495634
+bool isMouseOrTouchpadPresent() {

[sadrul, 2017/05/17 15:32:17]

IsMouseOrTouchpadPresent()

+  InputDeviceManager* input_manager = InputDeviceManager::GetInstance();
+  for (const ui::InputDevice& device : input_manager->GetTouchpadDevices()) {
+    if (device.enabled)
+      return true;
+  }
+  // We didn't find a touchpad then let's look if there is a mouse connected.
+  for (const ui::InputDevice& device : input_manager->GetMouseDevices()) {
+    if (device.enabled)
+      return true;
+  }
+  return false;
+}
+
+}  // namespace
+
 int GetAvailablePointerTypes() {
-  // Assume a mouse is there
-  int available_pointer_types = POINTER_TYPE_FINE;
+  int available_pointer_types = 0;
+  if (isMouseOrTouchpadPresent())
+    available_pointer_types |= POINTER_TYPE_FINE;
+
   if (IsTouchDevicePresent())
     available_pointer_types |= POINTER_TYPE_COARSE;
 
+  if (available_pointer_types == 0)
+    available_pointer_types = POINTER_TYPE_NONE;
+
   DCHECK(available_pointer_types);
   return available_pointer_types;
 }
 
-// TODO(mustaq@chromium.org): Use mouse detection logic. crbug.com/495634
 int GetAvailableHoverTypes() {
-  int available_hover_types = HOVER_TYPE_HOVER;
-  if (IsTouchDevicePresent())
-    available_hover_types |= HOVER_TYPE_NONE;
+  int available_hover_types = HOVER_TYPE_NONE;
+  if (isMouseOrTouchpadPresent())
+    available_hover_types |= HOVER_TYPE_HOVER;

[sadrul, 2017/05/17 15:32:17]

One sidenote: having both NONE and HOVER bits set is confusing.

[mustaq, 2017/05/17 16:46:54]

I agree this looks confusing but available_hover_types must reflect the union of
all input devices because the spec requires 'any-hover' to be true in both the
following cases for a device with mouse+touch:
  any-hover: none
  any-hover: hover

It is as if answering "yes" to the following two questions:
  Is there an input that doesn't support hover?
  Is there an input that supports hover?

https://drafts.csswg.org/mediaqueries-4/#any-input

So what we have here looks correct.

   return available_hover_types;
 }
 
-}  // namespace
-
 TouchScreensAvailability GetTouchScreensAvailability() {
   if (!IsTouchDevicePresent())
     return TouchScreensAvailability::NONE;
@@ -56,10 +73,6 @@ int MaxTouchPoints() {
   return max_touch;
 }
 
-std::pair<int, int> GetAvailablePointerAndHoverTypes() {
-  return std::make_pair(GetAvailablePointerTypes(), GetAvailableHoverTypes());
-}
-
 PointerType GetPrimaryPointerType(int available_pointer_types) {
   if (available_pointer_types & POINTER_TYPE_FINE)
     return POINTER_TYPE_FINE;