Propagate error messages to UI for blimp.

blimp/client/core/context/blimp_client_context_impl.h

Index: blimp/client/core/context/blimp_client_context_impl.h
diff --git a/blimp/client/core/context/blimp_client_context_impl.h b/blimp/client/core/context/blimp_client_context_impl.h
index d6e46c0e57495f712e089794e19cbd4a49f48304..fd0653d941356b7e95a14c7d4d1597cb4706c6fa 100644
--- a/blimp/client/core/context/blimp_client_context_impl.h
+++ b/blimp/client/core/context/blimp_client_context_impl.h
@@ -44,7 +44,8 @@ class TabControlFeature;
 class BlimpClientContextImpl
     : public BlimpClientContext,
       public BlimpSettingsDelegate,
-      public BlobImageSerializationProcessor::ErrorDelegate {
+      public BlobImageSerializationProcessor::ErrorDelegate,
+      public NetworkEventObserver {
  public:
   // The |io_thread_task_runner| must be the task runner to use for IO
   // operations.
@@ -99,6 +100,10 @@ class BlimpClientContextImpl
   // BlobImageSerializationProcessor::ErrorDelegate implementation.
   void OnImageDecodeError() override;
 
+  // NetworkEventObserver implementation.
+  void OnConnected() override;
+  void OnDisconnected(int result) override;
+
   // Provides functionality from the embedder.
   BlimpClientContextDelegate* delegate_ = nullptr;