update_engine: Rename "chromeos" -> "brillo" in include paths and namespaces

libchromeos is transitioning to libbrillo and chromeos namespaces
and include directory is changing to brillo.

Bug: 24872993
Change-Id: I770659a95be380a50fe3b2ba9f91d65818f40945
diff --git a/fake_file_writer.h b/fake_file_writer.h
index 4776db8..452b9d2 100644
--- a/fake_file_writer.h
+++ b/fake_file_writer.h
@@ -20,7 +20,7 @@
 #include <vector>
 
 #include <base/macros.h>
-#include <chromeos/secure_blob.h>
+#include <brillo/secure_blob.h>
 
 #include "update_engine/file_writer.h"
 
@@ -56,13 +56,13 @@
     return 0;
   }
 
-  const chromeos::Blob& bytes() {
+  const brillo::Blob& bytes() {
     return bytes_;
   }
 
  private:
   // The internal store of all bytes that have been written
-  chromeos::Blob bytes_;
+  brillo::Blob bytes_;
 
   // These are just to ensure FileWriter methods are called properly.
   bool was_opened_;