Adds hook for content embedders to get media::BrowserCdm*.

content/public/test/mock_render_process_host.h

Index: content/public/test/mock_render_process_host.h
diff --git a/content/public/test/mock_render_process_host.h b/content/public/test/mock_render_process_host.h
index 328625999d85f493dbe4ea67fee2fb216aeacccb..29088135364113ac23fafcbcb806ba62af0fb71f 100644
--- a/content/public/test/mock_render_process_host.h
+++ b/content/public/test/mock_render_process_host.h
@@ -88,6 +88,10 @@ class MockRenderProcessHost : public RenderProcessHost {
   void OnRemoveSubscription(unsigned int target) override;
   void SendUpdateValueState(
       unsigned int target, const gpu::ValueState& state) override;
+#if defined(ENABLE_BROWSER_CDMS)
+  media::BrowserCdm* GetBrowserCdm(int render_frame_id,
+                                   int cdm_id) const override;
+#endif
 
   // IPC::Sender via RenderProcessHost.
   bool Send(IPC::Message* msg) override;