Make the shell work in multiprocess mode some apps.

shell/context.h

Index: shell/context.h
diff --git a/shell/context.h b/shell/context.h
index 62c49c2f3ecf8b0a09e540e1db7516d05c912e03..b3f2510b7f3a0dba55de9dfa5449ee4853af9f7b 100644
--- a/shell/context.h
+++ b/shell/context.h
@@ -21,7 +21,8 @@ class ExternalApplicationListener;
 class NativeApplicationLoader;
 
 // The "global" context for the shell's main process.
-class Context : ApplicationManager::Delegate, embedder::ProcessDelegate {
+class Context : public ApplicationManager::Delegate,
+                public embedder::ProcessDelegate {
  public:
   Context();
   ~Context() override;