buffet: load standard GCD command definitions in CommandManager

Changed CommandManager to load the base command definitions
and use it as a base schema for loading device-specific commands
and make sure device vendors are not redefining standard commands
in breaking manner.

BUG=chromium:374861
TEST=USE=buffet P2_TEST_FILTER="buffet::*" FEATURES=test emerge-link platform2

Change-Id: I5f2d5500bc90ef918a8a6df1242bdd1fe3b78615
Reviewed-on: https://chromium-review.googlesource.com/209175
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>

buffet/commands/command_manager.h

diff --git a/buffet/commands/command_manager.h b/buffet/commands/command_manager.h
index 1700712..64037b8 100644
--- a/buffet/commands/command_manager.h
+++ b/buffet/commands/command_manager.h
@@ -5,7 +5,10 @@
 #ifndef BUFFET_COMMANDS_COMMAND_MANAGER_H_
 #define BUFFET_COMMANDS_COMMAND_MANAGER_H_
 
+#include <string>
+
 #include <base/basictypes.h>
+#include <base/files/file_path.h>
 
 #include "buffet/commands/command_dictionary.h"
 
@@ -21,7 +24,42 @@
   // Get the command definitions for the device.
   const CommandDictionary& GetCommandDictionary() const;
 
+  // Loads base/standard GCD command definitions.
+  // |json| is the full JSON schema of standard GCD commands. These commands
+  // are not necessarily supported by a particular device but rather
+  // all the standard commands defined by GCD standard for all known/supported
+  // device kinds.
+  // On success, returns true. Otherwise, |error| contains additional
+  // error information.
+  bool LoadBaseCommands(const base::DictionaryValue& json,
+                        ErrorPtr* error);
+
+  // Same as the overload above, but takes a path to a json file to read
+  // the base command definitions from.
+  bool LoadBaseCommands(const base::FilePath& json_file_path,
+                        ErrorPtr* error);
+
+  // Loads device command schema for particular category.
+  // See CommandDictionary::LoadCommands for detailed description of the
+  // parameters.
+  bool LoadCommands(const base::DictionaryValue& json,
+                    const std::string& category, ErrorPtr* error);
+
+  // Same as the overload above, but takes a path to a json file to read
+  // the base command definitions from. Also, the command category is
+  // derived from file name (without extension). So, if the path points to
+  // "power_manager.json", the command category used will be "power_manager".
+  bool LoadCommands(const base::FilePath& json_file_path,
+                    ErrorPtr* error);
+
  private:
+  // Helper function to load a JSON file that is expected to be
+  // an object/dictionary. In case of error, returns empty unique ptr and fills
+  // in error details in |error|.
+  std::unique_ptr<const base::DictionaryValue> LoadJsonDict(
+      const base::FilePath& json_file_path, ErrorPtr* error);
+
+  CommandDictionary base_dictionary_;  // Base/std command definitions/schemas.
   CommandDictionary dictionary_;  // Command definitions/schemas.
   DISALLOW_COPY_AND_ASSIGN(CommandManager);
 };