Implement getConfiguration in WebUSBDeviceImpl.

This USBDevice method allows a site to determine the current
configuration state of the device. A follow-up to this change will make
WebUSBDevice::getConfiguration a pure virtual method.

Blink change: https://codereview.chromium.org/1352283005/

BUG=492204

Review URL: https://codereview.chromium.org/1358763004

Cr-Commit-Position: refs/heads/master@{#350212}

content/renderer/usb/web_usb_device_impl.cc

@@ -23,6 +23,7 @@ namespace {
 const char kClaimInterfaceFailed[] = "Unable to claim interface.";
 const char kClearHaltFailed[] = "Unable to clear endpoint.";
 const char kDeviceNoAccess[] = "Access denied.";
+const char kDeviceNotConfigured[] = "Device not configured.";
 const char kDeviceNotOpened[] = "Device not opened.";
 const char kDeviceUnavailable[] = "Device unavailable.";
 const char kDeviceResetFailed[] = "Unable to reset the device.";
@@ -90,6 +91,16 @@ void OnDeviceClosed(
   callbacks.PassCallbacks()->onSuccess();
 }
 
+void OnGetConfiguration(
+    ScopedWebCallbacks<blink::WebUSBDeviceGetConfigurationCallbacks> callbacks,
+    uint8_t configuration_value) {
+  auto scoped_callbacks = callbacks.PassCallbacks();
+  if (configuration_value == 0)
+    RejectWithDeviceError(kDeviceNotConfigured, scoped_callbacks.Pass());
+  else
+    scoped_callbacks->onSuccess(configuration_value);
+}
+
 void HandlePassFailDeviceOperation(
     ScopedWebCallbacks<blink::WebCallbacks<void, const blink::WebUSBError&>>
         callbacks,
@@ -171,6 +182,17 @@ void WebUSBDeviceImpl::close(blink::WebUSBDeviceCloseCallbacks* callbacks) {
   }
 }
 
+void WebUSBDeviceImpl::getConfiguration(
+    blink::WebUSBDeviceGetConfigurationCallbacks* callbacks) {
+  auto scoped_callbacks = MakeScopedUSBCallbacks(callbacks);
+  if (!device_) {
+    RejectWithDeviceError(kDeviceNotOpened, scoped_callbacks.PassCallbacks());
+  } else {
+    device_->GetConfiguration(
+        base::Bind(&OnGetConfiguration, base::Passed(&scoped_callbacks)));
+  }
+}
+
 void WebUSBDeviceImpl::setConfiguration(
     uint8_t configuration_value,
     blink::WebUSBDeviceSetConfigurationCallbacks* callbacks) {

content/renderer/usb/web_usb_device_impl.h

@@ -32,6 +32,8 @@ class WebUSBDeviceImpl : public blink::WebUSBDevice {
   const blink::WebUSBDeviceInfo& info() const override;
   void open(blink::WebUSBDeviceOpenCallbacks* callbacks) override;
   void close(blink::WebUSBDeviceCloseCallbacks* callbacks) override;
+  void getConfiguration(
+      blink::WebUSBDeviceGetConfigurationCallbacks* callbacks) override;
   void setConfiguration(
       uint8_t configuration_value,
       blink::WebUSBDeviceSetConfigurationCallbacks* callbacks) override;

device/devices_app/usb/device_impl.cc

@@ -116,7 +116,7 @@ void DeviceImpl::GetDeviceInfo(const GetDeviceInfoCallback& callback) {
 
 void DeviceImpl::GetConfiguration(const GetConfigurationCallback& callback) {
   const UsbConfigDescriptor* config = device_->GetActiveConfiguration();
-  callback.Run(config ? ConfigurationInfo::From(*config) : nullptr);
+  callback.Run(config ? config->configuration_value : 0);
 }
 
 void DeviceImpl::Open(const OpenCallback& callback) {

device/devices_app/usb/public/interfaces/device.mojom

@@ -141,9 +141,9 @@ interface Device {
   // including the set of all available device configurations.
   GetDeviceInfo() => (DeviceInfo? info);
 
-  // Retrieves the device's currently active configuration. May return null if
-  // the device is unconfigured.
-  GetConfiguration() => (ConfigurationInfo? info);
+  // Retrieves the |configuration_value| of the device's currently active
+  // configuration. Will return 0 if the device is unconfigured.
+  GetConfiguration() => (uint8 value);
 
   // Opens the device. Methods below require the device be opened first.
   Open() => (OpenDeviceError error);