Adds Mojo IDL.

third_party/WebKit/Source/core/core_idl_files.gni

Index: third_party/WebKit/Source/core/core_idl_files.gni
diff --git a/third_party/WebKit/Source/core/core_idl_files.gni b/third_party/WebKit/Source/core/core_idl_files.gni
index e6a0ab4e91f6613a4b6d25be6bcc6309c8a07b65..5cf4523787cec8f57b22ae7873f8509cf134514c 100644
--- a/third_party/WebKit/Source/core/core_idl_files.gni
+++ b/third_party/WebKit/Source/core/core_idl_files.gni
@@ -289,6 +289,9 @@ core_idl_files = get_path_info([
                                  "input/InputDeviceCapabilities.idl",
                                  "inspector/InspectorOverlayHost.idl",
                                  "loader/appcache/ApplicationCache.idl",
+                                 "mojo/Mojo.idl",
+                                 "mojo/MojoHandle.idl",
+                                 "mojo/MojoWatcher.idl",
                                  "page/PagePopupController.idl",
                                  "page/scrolling/ScrollState.idl",
                                  "page/scrolling/ScrollStateCallback.idl",
@@ -563,6 +566,10 @@ core_dictionary_idl_files =
                     "html/track/TrackEventInit.idl",
                     "imagebitmap/ImageBitmapOptions.idl",
                     "input/InputDeviceCapabilitiesInit.idl",
+                    "mojo/MojoCreateMessagePipeResult.idl",
+                    "mojo/MojoHandleSignals.idl",
+                    "mojo/MojoReadMessageFlags.idl",
+                    "mojo/MojoReadMessageResult.idl",
                     "offscreencanvas/ImageEncodeOptions.idl",
                     "page/scrolling/ScrollStateInit.idl",
                     "timing/PerformanceObserverInit.idl",