[sensors] Add Generic Sensor platform unit tests.

device/BUILD.gn

Index: device/BUILD.gn
diff --git a/device/BUILD.gn b/device/BUILD.gn
index e4058278e7b084e002ac9de99dd81d3939ed45df..5baba4c37c6c91c44ba20bae4dfcb2e8868bea37 100644
--- a/device/BUILD.gn
+++ b/device/BUILD.gn
@@ -60,6 +60,7 @@ test("device_unittests") {
     "bluetooth/test/test_bluetooth_local_gatt_service_delegate.cc",
     "bluetooth/test/test_bluetooth_local_gatt_service_delegate.h",
     "gamepad/gamepad_provider_unittest.cc",
+    "generic_sensor/platform_sensor_provider_unittest.cc",
     "test/run_all_unittests.cc",
   ]
 
@@ -71,6 +72,8 @@ test("device_unittests") {
     "//device/bluetooth:mocks",
     "//device/gamepad",
     "//device/gamepad:test_helpers",
+    "//device/generic_sensor",
+    "//device/generic_sensor:mocks",
     "//device/geolocation:unittests",
     "//device/power_save_blocker",
     "//mojo/common",