buffet: Allow setting command results.

Next step in command results support: now there is
CommandInstance::SetResults method which allows results
modifications.

BUG=chromium:435607
TEST=cros_workon_make --test buffet

Change-Id: I1f5da9c3613a2996cea3f65f07945cc64bfeda2e
Reviewed-on: https://chromium-review.googlesource.com/231337
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Anton Muhin <antonm@chromium.org>
Commit-Queue: Anton Muhin <antonm@chromium.org>

buffet/commands/command_proxy_interface.h

diff --git a/buffet/commands/command_proxy_interface.h b/buffet/commands/command_proxy_interface.h
index f9e78d6..f434c75 100644
--- a/buffet/commands/command_proxy_interface.h
+++ b/buffet/commands/command_proxy_interface.h
@@ -7,6 +7,8 @@
 
 #include <string>
 
+#include "buffet/commands/schema_utils.h"
+
 namespace buffet {
 
 // This interface lets the command instance to update its proxy of command
@@ -16,6 +18,7 @@
  public:
   virtual ~CommandProxyInterface() = default;
 
+  virtual void OnResultsChanged(const native_types::Object& results) = 0;
   virtual void OnStatusChanged(const std::string& status) = 0;
   virtual void OnProgressChanged(int progress) = 0;
 };