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/extent_writer.h b/extent_writer.h
index 99b2c2f..83f40e0 100644
--- a/extent_writer.h
+++ b/extent_writer.h
@@ -20,7 +20,7 @@
 #include <vector>
 
 #include <base/logging.h>
-#include <chromeos/secure_blob.h>
+#include <brillo/secure_blob.h>
 
 #include "update_engine/file_descriptor.h"
 #include "update_engine/update_metadata.pb.h"
@@ -116,7 +116,7 @@
   bool EndImpl() override {
     if (bytes_written_mod_block_size_) {
       const size_t write_size = block_size_ - bytes_written_mod_block_size_;
-      chromeos::Blob zeros(write_size, 0);
+      brillo::Blob zeros(write_size, 0);
       TEST_AND_RETURN_FALSE(underlying_extent_writer_->Write(zeros.data(),
                                                              write_size));
     }