Add more generic filters to the chrome.hid.getDevices API.

extensions/common/api/hid.idl

Index: extensions/common/api/hid.idl
diff --git a/extensions/common/api/hid.idl b/extensions/common/api/hid.idl
index c6bb316311968db0d462bea3e9e8464635854e3a..e93f9c256485562fa2ca735326fcdf4b95b23416 100644
--- a/extensions/common/api/hid.idl
+++ b/extensions/common/api/hid.idl
@@ -42,10 +42,27 @@ namespace hid {
     long connectionId;
   };
 
-  // Searching criteria to enumerate devices with.
+  // Device matching criteria.
+  dictionary DeviceFilter {
+    long? vendorId;
+    // (checked only if the vendor ID matches)
+    long? productId;
+    long? usagePage;
+    // (checked only if the HID usage page matches)

[not at google - send to devlin, 2014/08/29 00:26:26]

This is all going to be generated as https://developer.chrome.com/apps/hid -
these comment in parenthesis are useful but would look better as part of a whole
document.

I don't know much about this stuff, but it seems like if certain properties are
only checked in certain conditions... this filter is a match-everything-specific
type thing?

+    long? usage;
+  };
+
+  // Options passed to <code>getDevices</code>.
   dictionary GetDevicesOptions {
-    long vendorId;
-    long productId;
+    // <b>Note:</b> Deprecated, equivalent to a filter with
+    // <code>vendorId</code> set.
+    long? vendorId;

[not at google - send to devlin, 2014/08/29 00:26:26]

There's a deprecated annotation:

[deprecated=Use a filter with $(ref:hid.DeviceFilter.vendorId vendorId)]

likewise.

+    // <b>Note:</b> Deprecated, equivalent to a filter with
+    // <code>productId</code> set.
+    long? productId;
+    // Devices matching any of the given filters will be returned. Providing an
+    // empty filter list will return all devices the app has permission for.
+    DeviceFilter[]? filters;
   };
 
   callback GetDevicesCallback = void (HidDeviceInfo[] devices);
@@ -67,8 +84,7 @@ namespace hid {
   callback SendCallback = void();
 
   interface Functions {
-    // Enumerate all the connected HID devices specified by the vendorId/
-    // productId/interfaceId tuple.
+    // Enumerate all the connected HID devices matching the given properties.
     // |options|: The properties to search for on target devices.
     // |callback|: Invoked with the <code>HidDeviceInfo</code> array on success.
     static void getDevices(GetDevicesOptions options,