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/test_utils.cc b/test_utils.cc
index 896097f..abf91d3 100644
--- a/test_utils.cc
+++ b/test_utils.cc
@@ -124,7 +124,7 @@
   return xattr_res == 0;
 }
 
-bool WriteFileVector(const string& path, const chromeos::Blob& data) {
+bool WriteFileVector(const string& path, const brillo::Blob& data) {
   return utils::WriteFile(path.c_str(), data.data(), data.size());
 }
 
@@ -155,8 +155,8 @@
   return true;
 }
 
-bool ExpectVectorsEq(const chromeos::Blob& expected,
-                     const chromeos::Blob& actual) {
+bool ExpectVectorsEq(const brillo::Blob& expected,
+                     const brillo::Blob& actual) {
   EXPECT_EQ(expected.size(), actual.size());
   if (expected.size() != actual.size())
     return false;
@@ -168,7 +168,7 @@
   return is_all_eq;
 }
 
-void FillWithData(chromeos::Blob* buffer) {
+void FillWithData(brillo::Blob* buffer) {
   size_t input_counter = 0;
   for (uint8_t& b : *buffer) {
     b = kRandomString[input_counter];