chrome.hid : enrich device info with Top-Level collections usages

device/hid/hid_service_mac.cc

Index: device/hid/hid_service_mac.cc
diff --git a/device/hid/hid_service_mac.cc b/device/hid/hid_service_mac.cc
index 3df7e592333e6b8ec9620d8f924456b951202572..08cd1293f511712dbfbd2cecc1d3737a363add7f 100644
--- a/device/hid/hid_service_mac.cc
+++ b/device/hid/hid_service_mac.cc
@@ -143,16 +143,30 @@ void HidServiceMac::PlatformAddDevice(IOHIDDeviceRef hid_device) {
       GetHidIntProperty(hid_device, CFSTR(kIOHIDVendorIDKey));
   device_info.product_id =
       GetHidIntProperty(hid_device, CFSTR(kIOHIDProductIDKey));
-  device_info.usage =
-      GetHidIntProperty(hid_device, CFSTR(kIOHIDPrimaryUsageKey));
-  device_info.usage_page =
-      GetHidIntProperty(hid_device, CFSTR(kIOHIDPrimaryUsagePageKey));
   device_info.input_report_size =
       GetHidIntProperty(hid_device, CFSTR(kIOHIDMaxInputReportSizeKey));
   device_info.output_report_size =
       GetHidIntProperty(hid_device, CFSTR(kIOHIDMaxOutputReportSizeKey));
   device_info.feature_report_size =
       GetHidIntProperty(hid_device, CFSTR(kIOHIDMaxFeatureReportSizeKey));
+  CFTypeRef deviceUsagePairsRaw =
+      IOHIDDeviceGetProperty(hid_device, CFSTR(kIOHIDDeviceUsagePairsKey));
+  CFArrayRef deviceUsagePairs =
+      base::mac::CFCast<CFArrayRef>(deviceUsagePairsRaw);
+  CFIndex deviceUsagePairsCount = CFArrayGetCount(deviceUsagePairs);
+  for (CFIndex i = 0; i < deviceUsagePairsCount; i++) {
+    HidUsageAndPage usage_and_page;
+    CFDictionaryRef deviceUsagePair = base::mac::CFCast<CFDictionaryRef>(
+        CFArrayGetValueAtIndex(deviceUsagePairs, i));
+    CFNumberRef usage_page_raw = base::mac::CFCast<CFNumberRef>(
+        CFDictionaryGetValue(deviceUsagePair, CFSTR(kIOHIDDeviceUsagePageKey)));
+    CFNumberGetValue(
+        usage_page_raw, kCFNumberSInt32Type, &usage_and_page.usage_page);
+    CFNumberRef usage_raw = base::mac::CFCast<CFNumberRef>(
+        CFDictionaryGetValue(deviceUsagePair, CFSTR(kIOHIDDeviceUsageKey)));
+    CFNumberGetValue(usage_raw, kCFNumberSInt32Type, &usage_and_page.usage);
+    device_info.usages.push_back(usage_and_page);

[Ken Rockot(use gerrit already), 2014/04/24 17:29:50]

Please just read values into local temporaries and construct the temporary HUAP
at the push_back callsite:

uint16_t usage;
UsagePage page;
..
.. foo(bar, baz, &usage);
.. foo(bar, baz, &page);
..
device_info.usages.push_back(HidUsageAndPage(usage, page));

[jracle (use Gerrit), 2014/04/24 19:21:28]

OK, makes more sense. Thanks for noticing it!

+  }
   device_info.product_name =
       GetHidStringProperty(hid_device, CFSTR(kIOHIDProductKey));
   device_info.serial_number =