Add support for blob urls for subresources.

content/common/renderer_host.mojom

Index: content/common/renderer_host.mojom
diff --git a/content/common/renderer_host.mojom b/content/common/renderer_host.mojom
new file mode 100644
index 0000000000000000000000000000000000000000..b2a271a57b483ee69db7d09e368f99d3f9182888
--- /dev/null
+++ b/content/common/renderer_host.mojom
@@ -0,0 +1,14 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+module content.mojom;
+
+import "content/common/url_loader_factory.mojom";
+
+// The primordial interface implemented by a render process host. This should be
+// used for implementing renderer-to-browser messages.
+interface RendererHost {
+  // Requests a URLLoaderFactory for the blob scheme.
+  GetBlobURLLoaderFactory(URLLoaderFactory& loader);
+};