Adds special support to the device manager for keyboards devices.

ui/events/device_data_manager.cc

Index: ui/events/device_data_manager.cc
diff --git a/ui/events/device_data_manager.cc b/ui/events/device_data_manager.cc
index d255b871abc80b10082d7408e92e25deafc7cb9a..fd9989c386826912c24c00f5922cda1d2e0359fa 100644
--- a/ui/events/device_data_manager.cc
+++ b/ui/events/device_data_manager.cc
@@ -13,6 +13,15 @@
 
 namespace ui {
 
+namespace {
+
+bool InputDeviceEquals(const ui::InputDevice& a,
+    const ui::InputDevice& b) {

[sky, 2014/10/20 22:18:43]

Make sure you run git cl format (this looks weird, not sure if git cl produced
this).

[rsadam, 2014/10/21 16:53:52]

Done.

+  return a.id == b.id;
+}
+
+}  // namespace
+
 // static
 DeviceDataManager* DeviceDataManager::instance_ = NULL;
 
@@ -111,11 +120,28 @@ int64_t DeviceDataManager::GetDisplayForTouchDevice(int touch_device_id) const {
 
 void DeviceDataManager::OnTouchscreenDevicesUpdated(
     const std::vector<TouchscreenDevice>& devices) {
+  if (devices.size() == touchscreen_devices_.size() &&

[sky, 2014/10/20 22:18:43]

Doesn't std::equals handle the length check?

[rsadam, 2014/10/21 16:53:52]

Removing this line causes a segfault. I did some digging
http://www.cplusplus.com/reference/algorithm/equal/ and based on the sample
algorithm there it does indeed seem that no length check is performed.

+      std::equal(devices.begin(), devices.end(),
+          touchscreen_devices_.begin(), InputDeviceEquals)) {
+    return;
+  }
   touchscreen_devices_ = devices;
+  FOR_EACH_OBSERVER(InputDeviceEventObserver,
+                  observers_,

[sky, 2014/10/20 22:18:43]

same comment about git cl format here and 143, spacing looks off.

[rsadam, 2014/10/21 16:53:52]

Done.

+                  OnTouchscreenDeviceConfigurationChanged());
+}
 
+void DeviceDataManager::OnKeyboardDevicesUpdated(
+    const std::vector<KeyboardDevice>& devices) {
+  if (devices.size() == keyboard_devices_.size() &&

[sky, 2014/10/20 22:18:43]

Same comment here about equals.

[rsadam, 2014/10/21 16:53:52]

Please see above.

+      std::equal(devices.begin(), devices.end(),
+          keyboard_devices_.begin(), InputDeviceEquals)) {
+    return;
+  }
+  keyboard_devices_ = devices;
   FOR_EACH_OBSERVER(InputDeviceEventObserver,
-                    observers_,
-                    OnInputDeviceConfigurationChanged());
+                  observers_,
+                  OnKeyboardDeviceConfigurationChanged());
 }
 
 void DeviceDataManager::AddObserver(InputDeviceEventObserver* observer) {