Generate param traits size methods for IPC files in chrome/ (and traits it depends on).

android_webview/common/android_webview_message_generator.cc

Index: android_webview/common/android_webview_message_generator.cc
diff --git a/android_webview/common/android_webview_message_generator.cc b/android_webview/common/android_webview_message_generator.cc
index d8b008069e00f1c915206809eb979ddb4929f1e8..cef229ba3f0e61027aa42484463176d32219c2df 100644
--- a/android_webview/common/android_webview_message_generator.cc
+++ b/android_webview/common/android_webview_message_generator.cc
@@ -14,6 +14,12 @@
 #include "ipc/struct_destructor_macros.h"
 #include "android_webview/common/android_webview_message_generator.h"
 
+// Generate param traits size methods.
+#include "ipc/param_traits_size_macros.h"
+namespace IPC {
+#include "android_webview/common/android_webview_message_generator.h"
+}  // namespace IPC
+
 // Generate param traits write methods.
 #include "ipc/param_traits_write_macros.h"
 namespace IPC {