Ignore HID elements in extraneous application collections on OSX

content/browser/gamepad/gamepad_platform_data_fetcher_mac.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/gamepad/gamepad_platform_data_fetcher_mac.h"
 
 #include <stdint.h>
 #include <string.h>
 
 #include "base/mac/foundation_util.h"
@@ skipping 138 matching lines @@
   InstanceFromContext(context)->DeviceRemove(ref);
 }
 
 void GamepadPlatformDataFetcherMac::ValueChangedCallback(void* context,
                                                          IOReturn result,
                                                          void* sender,
                                                          IOHIDValueRef ref) {
   InstanceFromContext(context)->ValueChanged(ref);
 }
 
+bool GamepadPlatformDataFetcherMac::CheckCollection(IOHIDElementRef element) {
+  // Check that a parent collection of this element matches one of the usage
+  // numbers that we are looking for.
+  while ((element = IOHIDElementGetParent(element)) != NULL) {
+    uint32_t usage_page = IOHIDElementGetUsagePage(element);
+    uint32_t usage = IOHIDElementGetUsage(element);
+    if (usage_page == kGenericDesktopUsagePage) {
+      if (usage == kJoystickUsageNumber ||
+          usage == kGameUsageNumber ||
+          usage == kMultiAxisUsageNumber) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
 bool GamepadPlatformDataFetcherMac::AddButtonsAndAxes(NSArray* elements,
                                                       size_t slot) {
   WebGamepad& pad = pad_state_[slot].data;
   AssociatedData& associated = associated_[slot];
   CHECK(!associated.is_xbox);
 
   pad.axesLength = 0;
   pad.buttonsLength = 0;
   pad.timestamp = 0;
   memset(pad.axes, 0, sizeof(pad.axes));
   memset(pad.buttons, 0, sizeof(pad.buttons));
 
   bool mapped_all_axes = true;
 
   for (id elem in elements) {
     IOHIDElementRef element = reinterpret_cast<IOHIDElementRef>(elem);
+    if (!CheckCollection(element))
+      continue;
+
     uint32_t usage_page = IOHIDElementGetUsagePage(element);
     uint32_t usage = IOHIDElementGetUsage(element);
     if (IOHIDElementGetType(element) == kIOHIDElementTypeInput_Button &&
         usage_page == kButtonUsagePage) {
       uint32_t button_index = usage - 1;
       if (button_index < WebGamepad::buttonsLengthCap) {
         associated.hid.button_elements[button_index] = element;
         pad.buttonsLength = std::max(pad.buttonsLength, button_index + 1);
       }
     }
@@ skipping 10 matching lines @@
         mapped_all_axes = false;
       }
     }
   }
 
   if (!mapped_all_axes) {
     // For axes who's usage puts them outside the standard axesLengthCap range.
     uint32_t next_index = 0;
     for (id elem in elements) {
       IOHIDElementRef element = reinterpret_cast<IOHIDElementRef>(elem);
+      if (!CheckCollection(element))
+        continue;
+
       uint32_t usage_page = IOHIDElementGetUsagePage(element);
       uint32_t usage = IOHIDElementGetUsage(element);
       if (IOHIDElementGetType(element) == kIOHIDElementTypeInput_Misc &&
           usage - kAxisMinimumUsageNumber >= WebGamepad::axesLengthCap &&
           usage_page <= kGameControlsUsagePage) {
         for (; next_index < WebGamepad::axesLengthCap; ++next_index) {
           if (associated.hid.axis_elements[next_index] == NULL)
             break;
         }
         if (next_index < WebGamepad::axesLengthCap) {
@@ skipping 286 matching lines @@
     pads->length = 0;
     return;
   }
 
   pads->length = WebGamepads::itemsLengthCap;
   for (size_t i = 0; i < WebGamepads::itemsLengthCap; ++i)
     MapAndSanitizeGamepadData(&pad_state_[i], &pads->items[i]);
 }
 
 }  // namespace content