Add a switch in BUILD rules to control the generation of type info for mojom files.

BUG= #596
R=rudominer@chromium.org

Review URL: https://codereview.chromium.org/1586123010 .
diff --git a/mojo/public/interfaces/bindings/tests/BUILD.gn b/mojo/public/interfaces/bindings/tests/BUILD.gn
index 425241a..e896b48 100644
--- a/mojo/public/interfaces/bindings/tests/BUILD.gn
+++ b/mojo/public/interfaces/bindings/tests/BUILD.gn
@@ -6,6 +6,8 @@
 
 mojom("test_interfaces") {
   testonly = true
+  # Some of those files are part of tests that check type info generation.
+  generate_type_info = true
   sources = [
     "math_calculator.mojom",
     "no_module.mojom",
diff --git a/mojo/public/tools/bindings/mojom.gni b/mojo/public/tools/bindings/mojom.gni
index 1a8118b..fe7dbd5 100644
--- a/mojo/public/tools/bindings/mojom.gni
+++ b/mojo/public/tools/bindings/mojom.gni
@@ -205,6 +205,12 @@
         args += [ "--compiler-version=1" ]
       }
 
+      if (defined(invoker.generate_type_info) && invoker.generate_type_info) {
+        args += [ "--generate-type-info" ]
+      } else {
+        args += [ "--no-generate-type-info" ]
+      }
+
       if (defined(invoker.import_dirs)) {
         foreach(import_dir, invoker.import_dirs) {
           args += [
diff --git a/mojo/public/tools/bindings/run_code_generators.py b/mojo/public/tools/bindings/run_code_generators.py
index c8c0eac..bdb2fe7 100755
--- a/mojo/public/tools/bindings/run_code_generators.py
+++ b/mojo/public/tools/bindings/run_code_generators.py
@@ -50,7 +50,7 @@
   parser.add_argument("--no-generate-type-info", dest="generate_type_info",
                       action="store_false",
                       help="do not generate mojom type descriptors")
-  parser.set_defaults(generate_type_info=True)
+  parser.set_defaults(generate_type_info=False)
 
   return parser.parse_known_args()