Decouple Power Monitor from //content.

content/test/BUILD.gn

Index: content/test/BUILD.gn
diff --git a/content/test/BUILD.gn b/content/test/BUILD.gn
index 50cef162868aaa032393fe756a05fef13ad288b3..b43b5bb1194fd6026da66b266428b3cb3853bc7e 100644
--- a/content/test/BUILD.gn
+++ b/content/test/BUILD.gn
@@ -1113,7 +1113,6 @@ test("content_unittests") {
     "../browser/notifications/notification_id_generator_unittest.cc",
     "../browser/notifications/platform_notification_context_unittest.cc",
     "../browser/notifications/type_converters_unittest.cc",
-    "../browser/power_monitor_message_broadcaster_unittest.cc",
     "../browser/power_usage_monitor_impl_unittest.cc",
     "../browser/presentation/presentation_service_impl_unittest.cc",
     "../browser/presentation/presentation_type_converters_unittest.cc",
@@ -1234,7 +1233,6 @@ test("content_unittests") {
     "../child/indexed_db/webidbcursor_impl_unittest.cc",
     "../child/memory/child_memory_coordinator_impl_unittest.cc",
     "../child/notifications/notification_data_conversions_unittest.cc",
-    "../child/power_monitor_broadcast_source_unittest.cc",
     "../child/resource_dispatcher_unittest.cc",
     "../child/service_worker/service_worker_dispatcher_unittest.cc",
     "../child/shared_memory_data_consumer_handle_unittest.cc",
@@ -1373,7 +1371,6 @@ test("content_unittests") {
     "//device/bluetooth:mocks",
     "//device/gamepad",
     "//device/gamepad:test_helpers",
-    "//device/power_monitor/public/interfaces",
     "//device/sensors/public/cpp",
     "//device/sensors/public/interfaces",
     "//gin",