Merge cdc_stream into asset_stream_manager (#26)

Adds start and stop commands to asset_stream_manager.
asset_stream_manager will be renamed to cdc_stream next.

asset_stream_manager/start_service_command.h

@@ -17,6 +17,10 @@
 #ifndef ASSET_STREAM_MANAGER_START_SERVICE_COMMAND_H_
 #define ASSET_STREAM_MANAGER_START_SERVICE_COMMAND_H_
 
+#include <memory>
+
+#include "absl/status/status.h"
+#include "absl/status/statusor.h"
 #include "asset_stream_manager/asset_stream_config.h"
 #include "asset_stream_manager/base_command.h"
 
@@ -34,9 +38,8 @@ class StartServiceCommand : public BaseCommand {
   absl::Status Run() override;
 
  private:
-  // Initializes LOG* logging.
-  // Depending on the flags, might log to console or to a file.
-  absl::Status InitLogging();
+  // Depending on the flags, returns a console or file logger.
+  absl::StatusOr<std::unique_ptr<Log>> GetLogger();
 
   // Runs the asset streaming service.
   absl::Status RunService();