API functions returning Promises should not throw exceptions.

Source/bindings/scripts/v8_methods.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 33 matching lines @@
 # Methods with any of these require custom method registration code in the
 # interface's configure*Template() function.
 CUSTOM_REGISTRATION_EXTENDED_ATTRIBUTES = frozenset([
     'DoNotCheckSecurity',
     'DoNotCheckSignature',
     'NotEnumerable',
     'Unforgeable',
 ])
 
 
-def argument_needs_try_catch(argument):
+def argument_needs_try_catch(argument, return_promise):
     idl_type = argument.idl_type
     base_type = not idl_type.native_array_element_type and idl_type.base_type
 
     return not (
         # These cases are handled by separate code paths in the
         # generate_argument() macro in Source/bindings/templates/methods.cpp.
         idl_type.is_callback_interface or
         base_type == 'SerializedScriptValue' or
         (argument.is_variadic and idl_type.is_wrapper_type) or
         # String and enumeration arguments converted using one of the
-        # TOSTRING_* macros in Source/bindings/core/v8/V8BindingMacros.h don't
-        # use a v8::TryCatch.
-        (base_type == 'DOMString' and not argument.is_variadic))
+        # TOSTRING_* macros except for _PROMISE variants in
+        # Source/bindings/core/v8/V8BindingMacros.h don't use a v8::TryCatch.
+        (base_type == 'DOMString' and not argument.is_variadic and
+         not return_promise))
 
 
 def use_local_result(method):
     extended_attributes = method.extended_attributes
     idl_type = method.idl_type
     return (has_extended_attribute_value(method, 'CallWith', 'ScriptState') or
             'ImplementedInPrivateScript' in extended_attributes or
             'RaisesException' in extended_attributes or
             idl_type.is_union_type or
             idl_type.is_explicit_nullable)
 
 
 def method_context(interface, method):
     arguments = method.arguments
     extended_attributes = method.extended_attributes
     idl_type = method.idl_type
     is_static = method.is_static
     name = method.name
+    return_promise = idl_type.name == 'Promise'
 
     idl_type.add_includes_for_type()
     this_cpp_value = cpp_value(interface, method, len(arguments))
 
     def function_template():
         if is_static:
             return 'functionTemplate'
         if 'Unforgeable' in extended_attributes:
             return 'instanceTemplate'
         return 'prototypeTemplate'
@@ skipping 19 matching lines @@
         includes.add('bindings/core/v8/BindingSecurity.h')
     is_custom_element_callbacks = 'CustomElementCallbacks' in extended_attributes
     if is_custom_element_callbacks:
         includes.add('core/dom/custom/CustomElementCallbackDispatcher.h')
 
     is_check_security_for_frame = (
         'CheckSecurity' in interface.extended_attributes and
         'DoNotCheckSecurity' not in extended_attributes)
     is_raises_exception = 'RaisesException' in extended_attributes
 
-    arguments_need_try_catch = any(argument_needs_try_catch(argument)
-                                   for argument in arguments)
+    arguments_need_try_catch = (
+        any(argument_needs_try_catch(argument, return_promise)
+            for argument in arguments))
 
     return {
         'activity_logging_world_list': v8_utilities.activity_logging_world_list(method),  # [ActivityLogging]
         'arguments': [argument_context(interface, method, argument, index)
                       for index, argument in enumerate(arguments)],
         'argument_declarations_for_private_script':
             argument_declarations_for_private_script(interface, method),
         'arguments_need_try_catch': arguments_need_try_catch,
         'conditional_string': v8_utilities.conditional_string(method),
         'cpp_type': (v8_types.cpp_template_type('Nullable', idl_type.cpp_type)
@@ skipping 57 matching lines @@
         'v8_set_return_value_for_main_world': v8_set_return_value(interface.name, method, this_cpp_value, for_main_world=True),
         'world_suffixes': ['', 'ForMainWorld'] if 'PerWorldBindings' in extended_attributes else [''],  # [PerWorldBindings],
     }
 
 
 def argument_context(interface, method, argument, index):
     extended_attributes = argument.extended_attributes
     idl_type = argument.idl_type
     this_cpp_value = cpp_value(interface, method, index)
     is_variadic_wrapper_type = argument.is_variadic and idl_type.is_wrapper_type
+    return_promise = (method.idl_type.name == 'Promise' if method.idl_type
+                                                        else False)
 
     if ('ImplementedInPrivateScript' in extended_attributes and
         not idl_type.is_wrapper_type and
         not idl_type.is_basic_type):
         raise Exception('Private scripts supports only primitive types and DOM wrappers.')
 
     return {
         'cpp_type': idl_type.cpp_type_args(extended_attributes=extended_attributes,
                                            raw_type=True,
                                            used_as_variadic_argument=argument.is_variadic),
@@ skipping 21 matching lines @@
         'is_nullable': idl_type.is_nullable,
         'is_optional': argument.is_optional,
         'is_variadic_wrapper_type': is_variadic_wrapper_type,
         'is_wrapper_type': idl_type.is_wrapper_type,
         'name': argument.name,
         'private_script_cpp_value_to_v8_value': idl_type.cpp_value_to_v8_value(
             argument.name, isolate='scriptState->isolate()',
             creation_context='scriptState->context()->Global()'),
         'v8_set_return_value': v8_set_return_value(interface.name, method, this_cpp_value),
         'v8_set_return_value_for_main_world': v8_set_return_value(interface.name, method, this_cpp_value, for_main_world=True),
-        'v8_value_to_local_cpp_value': v8_value_to_local_cpp_value(argument, index),
+        'v8_value_to_local_cpp_value': v8_value_to_local_cpp_value(argument, index, return_promise=return_promise),
         'vector_type': v8_types.cpp_ptr_type('Vector', 'HeapVector', idl_type.gc_type),
     }
 
 
 def argument_declarations_for_private_script(interface, method):
     argument_declarations = ['LocalFrame* frame']
     argument_declarations.append('%s* holderImpl' % interface.name)
     argument_declarations.extend(['%s %s' % (argument.idl_type.cpp_type_args(
         used_as_rvalue_type=True), argument.name) for argument in method.arguments])
     if method.idl_type.name != 'void':
@@ skipping 83 matching lines @@
             # result is of type Nullable<T>
             cpp_value = 'result.get()'
         else:
             cpp_value = 'result'
         release = idl_type.release
 
     script_wrappable = 'impl' if inherits_interface(interface_name, 'Node') else ''
     return idl_type.v8_set_return_value(cpp_value, extended_attributes, script_wrappable=script_wrappable, release=release, for_main_world=for_main_world)
 
 
-def v8_value_to_local_cpp_variadic_value(argument, index):
+def v8_value_to_local_cpp_variadic_value(argument, index, return_promise):
     assert argument.is_variadic
     idl_type = argument.idl_type
 
-    macro = 'TONATIVE_VOID_INTERNAL'
+    suffix = ''
+
+    macro = 'TONATIVE_VOID'
     macro_args = [
       argument.name,
       'toNativeArguments<%s>(info, %s)' % (idl_type.cpp_type, index),
     ]
 
-    return '%s(%s)' % (macro, ', '.join(macro_args))
+    if return_promise:
+        suffix += '_PROMISE'
+        macro_args.append('info')
+
+    suffix += '_INTERNAL'
+
+    return '%s%s(%s)' % (macro, suffix, ', '.join(macro_args))
 
 
-def v8_value_to_local_cpp_value(argument, index):
+def v8_value_to_local_cpp_value(argument, index, return_promise=False):
     extended_attributes = argument.extended_attributes
     idl_type = argument.idl_type
     name = argument.name
     if argument.is_variadic:
-        return v8_value_to_local_cpp_variadic_value(argument, index)
+        return v8_value_to_local_cpp_variadic_value(argument, index, return_promise)
     return idl_type.v8_value_to_local_cpp_value(extended_attributes, 'info[%s]' % index,
-                                                name, index=index, declare_variable=False)
+                                                name, index=index, declare_variable=False, return_promise=return_promise)
 
 
 ################################################################################
 # Auxiliary functions
 ################################################################################
 
 # [NotEnumerable]
 def property_attributes(method):
     extended_attributes = method.extended_attributes
     property_attributes_list = []
@@ skipping 14 matching lines @@
 
 
 def argument_default_cpp_value(argument):
     if not argument.default_value:
         return None
     return argument.idl_type.literal_cpp_value(argument.default_value)
 
 IdlType.union_arguments = property(lambda self: None)
 IdlUnionType.union_arguments = property(union_arguments)
 IdlArgument.default_cpp_value = property(argument_default_cpp_value)