update_engine: update to libbase 242728

Made update_engine link with libchrome-242728 and fixed compile
issues due to changes in namespaces and include file layout.

Also removed some of suppressed compiler warnings and fixed the
issues masked by them (e.g. mismatched printf-like specifiers).

Added -Wextra compiler option to enable additional useful warnings
to ensure more strict checking... Had to disable "unused-parameter"
though since we have a lot of functions (mainly in fakes) that do
not use all of their parameters.

BUG=chromium:351593
TEST=Unit tests passed.
CQ-DEPEND=CL:191721

Change-Id: I1aa63a48d5f1f4ea75ba6b00aec7aa5f3bad15c4
Reviewed-on: https://chromium-review.googlesource.com/191510
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Alex Vakulenko <avakulenko@chromium.org>

p2p_manager.h

diff --git a/p2p_manager.h b/p2p_manager.h
index 0636e07..0b393f2 100644
--- a/p2p_manager.h
+++ b/p2p_manager.h
@@ -9,9 +9,9 @@
 #include <vector>
 
 #include <base/callback.h>
-#include <base/file_path.h>
+#include <base/files/file_path.h>
 #include <base/memory/ref_counted.h>
-#include <base/time.h>
+#include <base/time/time.h>
 #include <policy/device_policy.h>
 #include <policy/libpolicy.h>
 
@@ -111,7 +111,7 @@
 
   // Gets a fully qualified path for the file identified by |file_id|.
   // If the file has not been shared already using the FileShare()
-  // method, an empty FilePath is returned - use FilePath::empty() to
+  // method, an empty base::FilePath is returned - use FilePath::empty() to
   // find out.
   virtual base::FilePath FileGetPath(const std::string& file_id) = 0;