Use built-in kMaxValue enumerator for LatencyInfo mojo enums.

There's no need to define _LAST enumerators, since Mojo provides these
automatically.

Bug: 742517
Change-Id: Ibafea09dd000cf14db4033790bef6a860b5030e6
Reviewed-on: https://chromium-review.googlesource.com/1159263Reviewed-by: Timothy Dresser <tdresser@chromium.org>
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580245}

ui/latency/mojo/latency_info.mojom

@@ -56,8 +56,6 @@ enum LatencyComponentType {
   // Timestamp when the frame is swapped (i.e. when the rendering caused by
   // input event actually takes effect).
   INPUT_EVENT_LATENCY_FRAME_SWAP_COMPONENT,
-  LATENCY_COMPONENT_TYPE_LAST =
-      INPUT_EVENT_LATENCY_FRAME_SWAP_COMPONENT,
 };
 
 enum SourceEventType {
@@ -70,7 +68,6 @@ enum SourceEventType {
   TOUCHPAD,
   FRAME,
   OTHER,
-  SOURCE_EVENT_TYPE_LAST = OTHER,
 };
 
 // See ui/latency/latency_info.h

ui/latency/mojo/latency_info_struct_traits.cc

@@ -201,7 +201,7 @@ EnumTraits<ui::mojom::LatencyComponentType, ui::LatencyComponentType>::ToMojom(
           INPUT_EVENT_LATENCY_FRAME_SWAP_COMPONENT;
   }
   NOTREACHED();
-  return ui::mojom::LatencyComponentType::LATENCY_COMPONENT_TYPE_LAST;
+  return ui::mojom::LatencyComponentType::kMaxValue;
 }
 
 // static

ui/latency/mojo/latency_info_struct_traits.h

@@ -11,16 +11,13 @@
 
 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::LatencyComponentType::kMaxValue) ==
+                  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");
+static_assert(static_cast<int>(ui::mojom::SourceEventType::kMaxValue) ==
+                  static_cast<int>(ui::SOURCE_EVENT_TYPE_LAST),
+              "Enum size mismatch");
 
 template <>
 struct ArrayTraits<ui::LatencyInfo::LatencyMap> {