[mojo] remove unnecessary buffer.h include

This CL reduced total include for ip_address_space.mojom-blink-forward.h
from 0.72MB to 0.66MB.

Bug: 862064
Change-Id: I2f7278db9f06158d63a1345cf503d6cf5819f484
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1609617
Auto-Submit: Takuto Ikuta <tikuta@chromium.org>
Commit-Queue: Ken Rockot <rockot@google.com>
Reviewed-by: Ken Rockot <rockot@google.com>
Cr-Commit-Position: refs/heads/master@{#659075}

mojo/public/cpp/bindings/lib/serialization_forward.h

@@ -8,6 +8,7 @@
 #include "base/optional.h"
 #include "mojo/public/cpp/bindings/array_traits.h"
 #include "mojo/public/cpp/bindings/enum_traits.h"
+#include "mojo/public/cpp/bindings/lib/buffer.h"
 #include "mojo/public/cpp/bindings/lib/template_util.h"
 #include "mojo/public/cpp/bindings/map_traits.h"
 #include "mojo/public/cpp/bindings/string_traits.h"

mojo/public/tools/bindings/generators/cpp_templates/module-forward.h.tmpl

@@ -39,6 +39,10 @@ namespace {{variant}} {
 #ifndef {{header_guard}}
 #define {{header_guard}}
 
+{% if all_enums|length -%}
+#include <stdint.h>
+{%- endif %}
+
 {% if structs|length -%}
 #include "mojo/public/cpp/bindings/struct_ptr.h"
 {%- endif %}
@@ -56,8 +60,6 @@ namespace {{variant}} {
 #include "mojo/public/cpp/bindings/pending_remote.h"
 #include "mojo/public/cpp/bindings/raw_ptr_impl_ref_traits.h"
 #include "mojo/public/cpp/bindings/thread_safe_interface_ptr.h"
-{%- else %}
-#include "mojo/public/cpp/bindings/lib/buffer.h"
 {%- endif %}
 
 {% if not disallow_native_types and structs|length %}