update_engine: Break UpdateEngineDaemon into their own implementations

It looks like Android and ChromeOS have completely different
implementation of the daemon. So instead of polluting the source with
USE_* flags, just break it into their own implementation files. At the
very least this allows deprecating USE_BINDER and USE_OMAHA flag
completely.

BUG=chromium:978672
TEST=unittest, cros flash two times.

Change-Id: Ia5c4f9274e275a2c1ba9334111b694514914a475
Reviewed-on: https://chromium-review.googlesource.com/1674583
Tested-by: Amin Hassani <ahassani@chromium.org>
Commit-Ready: Amin Hassani <ahassani@chromium.org>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
diff --git a/Android.bp b/Android.bp
index 9031913..d9f3524 100644
--- a/Android.bp
+++ b/Android.bp
@@ -29,12 +29,10 @@
 
     cflags: [
         "-DBASE_VER=576279",
-        "-DUSE_BINDER=1",
         "-DUSE_CHROME_NETWORK_PROXY=0",
         "-DUSE_CHROME_KIOSK_APP=0",
         "-DUSE_HWID_OVERRIDE=0",
         "-DUSE_MTD=0",
-        "-DUSE_OMAHA=0",
         "-D_FILE_OFFSET_BITS=64",
         "-D_POSIX_C_SOURCE=199309L",
         "-Wa,--noexecstack",
@@ -269,7 +267,7 @@
         ":libupdate_engine_aidl",
         "binder_service_android.cc",
         "certificate_checker.cc",
-        "daemon.cc",
+        "daemon_android.cc",
         "daemon_state_android.cc",
         "hardware_android.cc",
         "libcurl_http_fetcher.cc",