Make PointerDeviceObserver work under Ozone

chrome/browser/chromeos/system/pointer_device_observer.cc

Index: chrome/browser/chromeos/system/pointer_device_observer.cc
diff --git a/chrome/browser/chromeos/system/pointer_device_observer.cc b/chrome/browser/chromeos/system/pointer_device_observer.cc
index 29bbd6790a825ed12bdd11b2b67648d5c9d7ac8f..2de130553decf29919085e13c07dce74fb9debe2 100644
--- a/chrome/browser/chromeos/system/pointer_device_observer.cc
+++ b/chrome/browser/chromeos/system/pointer_device_observer.cc
@@ -9,6 +9,7 @@
 #include "base/bind_helpers.h"
 #include "chrome/browser/chromeos/system/input_device_settings.h"
 #include "content/public/browser/browser_thread.h"
+#include "ui/events/devices/device_data_manager.h"
 
 #if defined(USE_X11)
 #include "chrome/browser/chromeos/events/xinput_hierarchy_changed_event_listener.h"
@@ -27,6 +28,8 @@ PointerDeviceObserver::~PointerDeviceObserver() {
 #if defined(USE_X11)
   XInputHierarchyChangedEventListener::GetInstance()
       ->RemoveObserver(this);
+#elif defined(USE_OZONE)
+  ui::DeviceDataManager::GetInstance()->RemoveObserver(this);

[sadrul, 2015/02/03 15:29:04]

There's no reason to add this ifdef. We should just remove
XInputHierarchyChangedEventListener and DeviceHierarchyObserver, and use the
same pattern (i.e. use InputDeviceEventObserver) on X11. (you can reference
issue 360377)

[pkotwicz, 2015/02/03 16:50:14]

I completely agree. I am not doing this as part of this CL because the bug is
marked as M41 release-block stable. I think that it will be easier to convince
dharani@ that the CL can be merged back if I do not modify the X11 code path. I
can file a bug and reference the bug in the code.

If we merge back this CL, we will need to merge back at least some of
https://codereview.chromium.org/868043003

dharani@ seems keen to have this bug fixed in M41. Do you have any suggestions
as to how to make this CL simpler?

Should I investigate in what the consequences would be if the all of the users
of PointerDeviceObserver thought that the mouse and touchpad always existed on
Ozone in M41?

[sadrul, 2015/02/03 17:33:04]

Unfortunately no. Providing default no-op impls on the new observer methods
(which I think we should always do; it doesn't make sense to force observers to
override everything) would make the line count smaller. But I don't know how
much that would help in terms of making this simple.
I am unsure. You can get confirmation from dharani@

 #endif
 }
 
@@ -34,6 +37,8 @@ void PointerDeviceObserver::Init() {
 #if defined(USE_X11)
   XInputHierarchyChangedEventListener::GetInstance()
       ->AddObserver(this);
+#elif defined(USE_OZONE)
+  ui::DeviceDataManager::GetInstance()->AddObserver(this);
 #endif
 }
 
@@ -54,6 +59,14 @@ void PointerDeviceObserver::DeviceHierarchyChanged() {
   CheckDevices();
 }
 
+void PointerDeviceObserver::OnMouseDeviceConfigurationChanged() {
+  CheckDevices();
+}
+
+void PointerDeviceObserver::OnTouchpadDeviceConfigurationChanged() {
+  CheckDevices();
+}
+
 void PointerDeviceObserver::CheckTouchpadExists() {
   InputDeviceSettings::Get()->TouchpadExists(
       base::Bind(&PointerDeviceObserver::OnTouchpadExists,