Add chrome.usb.getConfigurations function.

Add a new extension function that returns all of the configuration
descriptors from the provided USB device. In addition to exposing this
useful information to applications (as otherwise they would need to call
chrome.usb.setConfiguration blindly to set a non-default configuration)
it is also now available without having to call chrome.usb.openDevice
first.

BUG=531586

Review URL: https://codereview.chromium.org/1357523005

Cr-Commit-Position: refs/heads/master@{#349592}

1 files changed, 17 insertions, 1 deletions

diff --git a/extensions/test/data/api_test/usb/device_handling/test.js b/extensions/test/data/api_test/usb/device_handling/test.js
index a546564..5914f6a 100644
--- a/extensions/test/data/api_test/usb/device_handling/test.js
+++ b/extensions/test/data/api_test/usb/device_handling/test.js
@@ -22,6 +22,22 @@ function getDevices() {
   });
 }
 
+function getConfigurations() {
+  usb.getDevices({}, function(devices) {
+    chrome.test.assertNoLastError();
+    chrome.test.assertEq(1, devices.length);
+    chrome.usb.getConfigurations(devices[0], function(configs) {
+      chrome.test.assertNoLastError();
+      chrome.test.assertEq(2, configs.length);
+      chrome.test.assertTrue(configs[0].active);
+      chrome.test.assertEq(1, configs[0].configurationValue);
+      chrome.test.assertFalse(configs[1].active);
+      chrome.test.assertEq(2, configs[1].configurationValue);
+      chrome.test.succeed();
+    });
+  });
+}
+
 function explicitCloseDevice() {
   usb.findDevices({
       vendorId: 0,
@@ -33,5 +49,5 @@ function explicitCloseDevice() {
 }
 
 chrome.test.runTests([
-    getDevices, explicitCloseDevice
+    getDevices, getConfigurations, explicitCloseDevice
 ]);