Implement Mojo SyncLoad

content/common/url_loader_factory.mojom

Index: content/common/url_loader_factory.mojom
diff --git a/content/common/url_loader_factory.mojom b/content/common/url_loader_factory.mojom
index 0cd0cb872ef5c6b0f18a38a4a4fc0b2222f6aeaf..5b7aab4c80a89049d8f1fc9a882e7c774e79317b 100644
--- a/content/common/url_loader_factory.mojom
+++ b/content/common/url_loader_factory.mojom
@@ -6,6 +6,9 @@ module content.mojom;
 
 import "url_loader.mojom";
 
+[Native]
+struct URLSyncLoadResult;
+
 interface URLLoaderFactory {
   // Creats a URLLoader and starts loading with the given |request|. |client|'s
   // method will be called when certain events related to that loading
@@ -16,4 +19,11 @@ interface URLLoaderFactory {
                        int32 request_id,
                        URLRequest request,
                        URLLoaderClient client);
-};
+
+  // Loads the resource for the given |request| synchronously.
+  // |request_id| is for compatibility with the existing Chrome IPC.
+  [Sync] SyncLoad(int32 routing_id,
+                  int32 request_id,
+                  URLRequest request)
+      => (URLSyncLoadResult result);
+};