tools: put all host-side code into host_tool namespace

To avoid confusion and organize the code itself more cleanly, place the
host-side code into its own namespace.

Change-Id: I573eb0494eb59874adb1d1eadc502499e928e396
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/test/data_interface_mock.hpp b/test/data_interface_mock.hpp
index 6335ad2..3e8f24a 100644
--- a/test/data_interface_mock.hpp
+++ b/test/data_interface_mock.hpp
@@ -4,6 +4,9 @@
 
 #include <gmock/gmock.h>
 
+namespace host_tool
+{
+
 class DataInterfaceMock : public DataInterface
 {
 
@@ -14,3 +17,5 @@
     MOCK_CONST_METHOD0(supportedType,
                        blobs::FirmwareBlobHandler::UpdateFlags());
 };
+
+} // namespace host_tool