update_engine: Include quick_fix_build_token in updatecheck request body

Get the value of the new device policy which is included in
AutoUpdateSettings as quick_fix_build_token, and include it
in the update request body if value is set.

BUG=chromium:932465
TEST=./build_packages --board=amd64-generic && \
     cros_run_unit_tests --board=amd64-generic --packages update_engine
Cq-Depend: chromium:1571634

Change-Id: Iaca35a08d973616a058864a11896ef9305d00174
Reviewed-on: https://chromium-review.googlesource.com/1581519
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Askar Aitzhan <askaraitzhan@google.com>
Reviewed-by: Nicolas Norvez <norvez@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
diff --git a/omaha_request_params.h b/omaha_request_params.h
index 2d2ab69..f3f68f4 100644
--- a/omaha_request_params.h
+++ b/omaha_request_params.h
@@ -193,6 +193,13 @@
   inline void set_is_install(bool is_install) { is_install_ = is_install; }
   inline bool is_install() const { return is_install_; }
 
+  inline void set_autoupdate_token(const std::string& token) {
+    autoupdate_token_ = token;
+  }
+  inline const std::string& autoupdate_token() const {
+    return autoupdate_token_;
+  }
+
   // Returns the app id corresponding to the current value of the
   // download channel.
   virtual std::string GetAppId() const;
@@ -371,6 +378,11 @@
   // current active partition instead of the inactive partition.
   bool is_install_;
 
+  // Token used when making an update request for a specific build.
+  // For example: Token for a Quick Fix Build:
+  // https://www.chromium.org/administrators/policy-list-3#DeviceQuickFixBuildToken.
+  std::string autoupdate_token_;
+
   DISALLOW_COPY_AND_ASSIGN(OmahaRequestParams);
 };