[mojo-bindings] Attribute "native" -> "Native"

We conventionally use CamelCase attribute names.

BUG=581169
R=yzshen@chromium.org

Review URL: https://codereview.chromium.org/1637903002

Cr-Commit-Position: refs/heads/master@{#371528}

mojo/public/interfaces/bindings/tests/test_native_types.mojom

@@ -8,7 +8,7 @@ import "mojo/public/interfaces/bindings/tests/rect.mojom";
 
 // Used to verify that structs can be declared with no body in mojom.
 
-[native=True]
+[Native=True]
 struct PickledStruct;
 
 interface PicklePasser {

mojo/public/tools/bindings/pylib/mojom/generate/data.py

@@ -225,12 +225,12 @@ def StructFromData(module, data):
     struct.fields_data = data['fields']
   struct.attributes = data.get('attributes')
 
-  # Enforce that a [native=True] attribute is set to make native-only struct
+  # Enforce that a [Native=True] attribute is set to make native-only struct
   # declarations more explicit.
   if struct.native_only:
-    if not struct.attributes or not struct.attributes.get('native', False):
+    if not struct.attributes or not struct.attributes.get('Native', False):
       raise Exception("Native-only struct declarations must include a " +
-                      "native=True attribute.")
+                      "Native=True attribute.")
 
   return struct