Adding static asserts to LatencyInfo struct traits.

Asserts ensure that the number of items in corresponding ui and mojom enums matches each other.

BUG=NONE

Review-Url: https://codereview.chromium.org/2856623002
Cr-Commit-Position: refs/heads/master@{#468408}

ui/latency/mojo/latency_info_struct_traits.h

@@ -11,6 +11,17 @@
 
 namespace mojo {
 
+static_assert(
+    static_cast<int>(
+        ui::mojom::LatencyComponentType::LATENCY_COMPONENT_TYPE_LAST) ==
+        static_cast<int>(ui::LATENCY_COMPONENT_TYPE_LAST),
+    "Enum size mismatch");
+
+static_assert(
+    static_cast<int>(ui::mojom::SourceEventType::SOURCE_EVENT_TYPE_LAST) ==
+        static_cast<int>(ui::SOURCE_EVENT_TYPE_LAST),
+    "Enum size mismatch");
+
 template <>
 struct ArrayTraits<ui::LatencyInfo::LatencyMap> {
   using Element = ui::LatencyInfo::LatencyMap::value_type;