Dart: Allows the mojom package's generate script to download .mojoms.

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

Index: mojo/public/tools/bindings/generators/mojom_dart_generator.py
diff --git a/mojo/public/tools/bindings/generators/mojom_dart_generator.py b/mojo/public/tools/bindings/generators/mojom_dart_generator.py
index 87c16ef8819e3f7c3ccce2122f5d944e7872f73b..c324c9c35d269976d3e860b218f00773231f0de4 100644
--- a/mojo/public/tools/bindings/generators/mojom_dart_generator.py
+++ b/mojo/public/tools/bindings/generators/mojom_dart_generator.py
@@ -9,6 +9,7 @@ import re
 import shutil
 import sys
 
+import mojom.fileutil as fileutil
 import mojom.generate.constant_resolver as resolver
 import mojom.generate.generator as generator
 import mojom.generate.module as mojom
@@ -421,20 +422,25 @@ class Generator(generator.Generator):
   def GenerateFiles(self, args):
     elements = self.module.namespace.split('.')
     elements.append("%s.dart" % self.module.name)
-    path = os.path.join("dart-pkg", "mojom/lib", *elements)
-    self.Write(self.GenerateLibModule(args), path)
-    path = os.path.join("dart-gen", "mojom/lib", *elements)
-    self.Write(self.GenerateLibModule(args), path)
+
+    lib_module = self.GenerateLibModule(args)
+    pkg_path = os.path.join("dart-pkg", "mojom/lib", *elements)
+    self.Write(lib_module, pkg_path)
+
+    gen_path = os.path.join("dart-gen", "mojom/lib", *elements)
+    full_gen_path = os.path.join(self.output_dir, gen_path)
+    self.Write(lib_module, gen_path)
+
     link = self.MatchMojomFilePath("%s.dart" % self.module.name)
-    if os.path.exists(os.path.join(self.output_dir, link)):
-      os.unlink(os.path.join(self.output_dir, link))
+    full_link_path = os.path.join(self.output_dir, link)
+    if os.path.exists(full_link_path):
+      os.unlink(full_link_path)
+    fileutil.EnsureDirectoryExists(os.path.dirname(full_link_path))
     try:
       if sys.platform == "win32":
-        shutil.copy(os.path.join(self.output_dir, path),
-                    os.path.join(self.output_dir, link))
+        shutil.copy(full_gen_path, full_link_path)
       else:
-        os.symlink(os.path.join(self.output_dir, path),
-                   os.path.join(self.output_dir, link))
+        os.symlink(full_gen_path, full_link_path)
     except OSError as e:
       # Errno 17 is file already exists. If the link fails because file already
       # exists assume another instance of this script tried to create the same