[mojo] Add testing support for DocumentInterfaceBroker to RenderFrameImpl

This change adds a way of overriding RenderFrameImpl's document interface
broker with a custom implementation.

Bug: 718652
Change-Id: Ia1fb901d0188858e67b930121d79e099506a167a
Reviewed-on: https://chromium-review.googlesource.com/c/1464923
Commit-Queue: Oksana Zhuravlova <[email protected]>
Reviewed-by: Alex Moshchuk <[email protected]>
Cr-Commit-Position: refs/heads/master@{#634514}
diff --git a/content/renderer/render_frame_impl.h b/content/renderer/render_frame_impl.h
index 21f63baf..b14e43bfe 100644
--- a/content/renderer/render_frame_impl.h
+++ b/content/renderer/render_frame_impl.h
@@ -942,6 +942,10 @@
   void DidCancelResponse(int request_id);
   void DidReceiveTransferSizeUpdate(int request_id, int received_data_length);
 
+  // Used in tests to override DocumentInterfaceBroker's methods
+  void SetDocumentInterfaceBrokerForTesting(
+      blink::mojom::DocumentInterfaceBrokerPtr test_broker);
+
  protected:
   explicit RenderFrameImpl(CreateParams params);