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..b555a3cdfb683899295eac4791406f1149664a42 100644
--- a/ui/base/touch/touch_device_linux.cc
+++ b/ui/base/touch/touch_device_linux.cc
@@ -15,23 +15,37 @@ bool IsTouchDevicePresent() {
   return !InputDeviceManager::GetInstance()->GetTouchscreenDevices().empty();
 }
 
-// TODO(mustaq@chromium.org): Use mouse detection logic. crbug.com/495634
+bool 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;
+}
+
 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;
-  return available_hover_types;
+  return isMouseOrTouchpadPresent() ? HOVER_TYPE_HOVER : HOVER_TYPE_NONE;

[mustaq, 2017/04/24 17:58:04]

For mouse+touch case, the return value should be HOVER|NONE as before.

 }
 
 }  // namespace
@@ -56,7 +70,21 @@ int MaxTouchPoints() {
   return max_touch;
 }
 
+bool return_available_pointer_and_hover_types_for_testing = false;

[mustaq, 2017/04/24 17:58:04]

This code duplication with touch_device_win.cc looks odd. Since this testing
code is platform independent, I suggest moving all test specific code (including
a dummy |GetAvailablePointerAndHoverTypes()| into a separate source file
touch_device_unittest.cc, and including the new file in the "ui_base_unittests"
rule in ui/base/BUILD.gn along with appropriate "sources -= touch_device_*"
rules.

+int available_pointer_types_for_testing = POINTER_TYPE_NONE;
+int available_hover_types_for_testing = HOVER_TYPE_NONE;
+
+void SetAvailablePointerAndHoverTypesForTesting(int available_pointer_types,
+                                                int available_hover_types) {
+  return_available_pointer_and_hover_types_for_testing = true;
+  available_pointer_types_for_testing = available_pointer_types;
+  available_hover_types_for_testing = available_hover_types;
+}
+
 std::pair<int, int> GetAvailablePointerAndHoverTypes() {
+  if (return_available_pointer_and_hover_types_for_testing)
+    return std::make_pair(available_pointer_types_for_testing,
+                          available_hover_types_for_testing);
   return std::make_pair(GetAvailablePointerTypes(), GetAvailableHoverTypes());
 }