Fix the blimp settings crash.

blimp/client/public/blimp_client_context.h

 // Copyright 2016 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.
 
 #ifndef BLIMP_CLIENT_PUBLIC_BLIMP_CLIENT_CONTEXT_H_
 #define BLIMP_CLIENT_PUBLIC_BLIMP_CLIENT_CONTEXT_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 48 matching lines @@
 
   // Register Blimp prefs. The implementation of this function depends on
   // whether the core or dummy implementation of Blimp has been linked in.
   static void RegisterPrefs(PrefRegistrySimple* registry);
 
   // Apply blimp command-line switches to the corresponding preferences of the
   // blimp's own switch map.
   static void ApplyBlimpSwitches(CommandLinePrefStore* store);
 
   // The delegate provides all the required functionality from the embedder.
+  // The context must be initialized with a |delegate| before it can be used.
   virtual void SetDelegate(BlimpClientContextDelegate* delegate) = 0;
 
   // Creates a new BlimpContents that will be shown in |window|.
   // TODO(mlliu): Currently we want to have a single BlimpContents. If there is
   // an existing contents, return nullptr (http://crbug.com/642558).
   virtual std::unique_ptr<BlimpContents> CreateBlimpContents(
       gfx::NativeWindow window) = 0;
 
   // Start authentication flow and connection to engine.
   virtual void Connect() = 0;
   virtual void ConnectWithAssignment(const Assignment& assignment) = 0;
 
  protected:
   BlimpClientContext() = default;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(BlimpClientContext);
 };
 
 }  // namespace client
 }  // namespace blimp
 
 #endif  // BLIMP_CLIENT_PUBLIC_BLIMP_CLIENT_CONTEXT_H_