Mojo C++ bindings: support mapping T and T? differently.

mojo/public/tools/bindings/generators/mojom_cpp_generator.py

Index: mojo/public/tools/bindings/generators/mojom_cpp_generator.py
diff --git a/mojo/public/tools/bindings/generators/mojom_cpp_generator.py b/mojo/public/tools/bindings/generators/mojom_cpp_generator.py
index f4daef8f2321a8831ee2a4260efde15fa755067d..c6b0ade9e1df98aae20f963114dcc6b71f74a9bc 100644
--- a/mojo/public/tools/bindings/generators/mojom_cpp_generator.py
+++ b/mojo/public/tools/bindings/generators/mojom_cpp_generator.py
@@ -153,8 +153,17 @@ def GetCppPodType(kind):
   return _kind_to_cpp_type[kind]
 
 def GetCppWrapperType(kind):
+  def _AddOptional(type_name):
+    pattern = "WTF::Optional<%s>" if _for_blink else "base::Optional<%s>"
+    return pattern % type_name
+
   if IsTypemappedKind(kind):
-    return GetNativeTypeName(kind)
+    type_name = GetNativeTypeName(kind)
+    if (mojom.IsNullableKind(kind) and
+        not _current_typemap[GetFullMojomNameForKind(kind)][
+           "nullable_is_same_type"]):
+      type_name = _AddOptional(type_name)
+    return type_name
   if mojom.IsEnumKind(kind):
     return GetNameForKind(kind)
   if mojom.IsStructKind(kind) or mojom.IsUnionKind(kind):
@@ -162,23 +171,19 @@ def GetCppWrapperType(kind):
   if mojom.IsArrayKind(kind):
     pattern = None
     if _use_new_wrapper_types:
+      pattern = "WTF::Vector<%s>" if _for_blink else "std::vector<%s>"
       if mojom.IsNullableKind(kind):
-        pattern = ("WTF::Optional<WTF::Vector<%s>>" if _for_blink else
-            "base::Optional<std::vector<%s>>")
-      else:
-        pattern = "WTF::Vector<%s>" if _for_blink else "std::vector<%s>"
+        pattern = _AddOptional(pattern)
     else:
       pattern = "mojo::WTFArray<%s>" if _for_blink else "mojo::Array<%s>"
     return pattern % GetCppWrapperType(kind.kind)
   if mojom.IsMapKind(kind):
     pattern = None
     if _use_new_wrapper_types:
+      pattern = ("WTF::HashMap<%s, %s>" if _for_blink else
+                 "std::unordered_map<%s, %s>")
       if mojom.IsNullableKind(kind):
-        pattern = ("WTF::Optional<WTF::HashMap<%s, %s>>" if _for_blink else
-                   "base::Optional<std::unordered_map<%s, %s>>")
-      else:
-        pattern = ("WTF::HashMap<%s, %s>" if _for_blink else
-                   "std::unordered_map<%s, %s>")
+        pattern = _AddOptional(pattern)
     else:
       pattern = "mojo::WTFMap<%s, %s>" if _for_blink else "mojo::Map<%s, %s>"
     return pattern % (GetCppWrapperType(kind.key_kind),
@@ -196,8 +201,8 @@ def GetCppWrapperType(kind):
       return "WTF::String"
     if not _use_new_wrapper_types:
       return "mojo::String"
-    return ("base::Optional<std::string>" if mojom.IsNullableKind(kind) else
-            "std::string")
+    type_name = "std::string"
+    return _AddOptional(type_name) if mojom.IsNullableKind(kind) else type_name
   if mojom.IsGenericHandleKind(kind):
     return "mojo::ScopedHandle"
   if mojom.IsDataPipeConsumerKind(kind):