--- a/toolkit/components/telemetry/TelemetryPing.jsm
+++ b/toolkit/components/telemetry/TelemetryPing.jsm
@@ -209,43 +209,34 @@ this.TelemetryPing = Object.freeze({
     PREF_SERVER: PREF_SERVER,
     PREF_PREVIOUS_BUILDID: PREF_PREVIOUS_BUILDID,
   }),
   /**
    * Used only for testing purposes.
    */
   reset: function() {
     this.uninstall();
-    Impl._clientID = null;
     return this.setup();
   },
   /**
    * Used only for testing purposes.
    */
   setup: function() {
     return Impl.setupChromeProcess(true);
   },
-
   /**
    * Used only for testing purposes.
    */
   uninstall: function() {
     try {
       Impl.uninstall();
     } catch (ex) {
       // Ignore errors
     }
   },
-
-  /**
-   * Used only for testing purposes.
-   */
-  shutdown: function() {
-    return Impl.shutdown(true);
-  },
   /**
    * Descriptive metadata
    *
    * @param  reason
    *         The reason for the telemetry ping, this will be included in the
    *         returned metadata,
    * @return The metadata as a JS object
    */
@@ -1029,17 +1020,20 @@ let Impl = {
     // id from disk.
     // We try to cache it in prefs to avoid this, even though this may
     // lead to some stale client ids.
     this._clientID = Preferences.get(PREF_CACHED_CLIENTID, null);
 
     AsyncShutdown.sendTelemetry.addBlocker(
       "Telemetry: shutting down",
       function condition(){
-        this.shutdown();
+        this.uninstall();
+        if (Telemetry.canSend) {
+          return this.savePendingPings();
+        }
       }.bind(this));
 
     Services.obs.addObserver(this, "sessionstore-windows-restored", false);
 #ifdef MOZ_WIDGET_ANDROID
     Services.obs.addObserver(this, "application-background", false);
 #endif
     Services.obs.addObserver(this, "xul-window-visible", false);
     this._hasWindowRestoredObserver = true;
@@ -1176,16 +1170,17 @@ let Impl = {
     }
     if (this._hasXulWindowVisibleObserver) {
       Services.obs.removeObserver(this, "xul-window-visible");
       this._hasXulWindowVisibleObserver = false;
     }
 #ifdef MOZ_WIDGET_ANDROID
     Services.obs.removeObserver(this, "application-background", false);
 #endif
+    this._clientID = null;
   },
 
   getPayload: function getPayload() {
     // This function returns the current Telemetry payload to the caller.
     // We only gather startup info once.
     if (Object.keys(this._slowSQLStartup).length == 0) {
       this.gatherStartupHistograms();
       this._slowSQLStartup = Telemetry.slowSQL;
@@ -1308,21 +1303,9 @@ let Impl = {
       break;
 #endif
     }
   },
 
   get clientID() {
     return this._clientID;
   },
-
-  /**
-   * This tells TelemetryPing to uninitialize and save any pending pings.
-   * @param testing Optional. If true, always saves the ping whether Telemetry
-   *                can send pings or not, which is used for testing.
-   */
-  shutdown: function(testing = false) {
-    this.uninstall();
-    if (Telemetry.canSend || testing) {
-      return this.savePendingPings();
-    }
-  },
 };

--- a/toolkit/components/telemetry/tests/unit/test_TelemetryPing.js
+++ b/toolkit/components/telemetry/tests/unit/test_TelemetryPing.js
@@ -17,17 +17,16 @@ Cu.import("resource://testing-common/htt
 Cu.import("resource://gre/modules/Services.jsm");
 Cu.import("resource://gre/modules/LightweightThemeManager.jsm", this);
 Cu.import("resource://gre/modules/XPCOMUtils.jsm", this);
 Cu.import("resource://gre/modules/TelemetryPing.jsm", this);
 Cu.import("resource://gre/modules/TelemetryFile.jsm", this);
 Cu.import("resource://gre/modules/Task.jsm", this);
 Cu.import("resource://gre/modules/Promise.jsm", this);
 Cu.import("resource://gre/modules/Preferences.jsm");
-Cu.import("resource://gre/modules/osfile.jsm", this);
 
 const IGNORE_HISTOGRAM = "test::ignore_me";
 const IGNORE_HISTOGRAM_TO_CLONE = "MEMORY_HEAP_ALLOCATED";
 const IGNORE_CLONED_HISTOGRAM = "test::ignore_me_also";
 const ADDON_NAME = "Telemetry test addon";
 const ADDON_HISTOGRAM = "addon-histogram";
 // Add some unicode characters here to ensure that sending them works correctly.
 const FLASH_VERSION = "\u201c1.1.1.1\u201d";
@@ -617,30 +616,16 @@ add_task(function* test_runOldPingFile()
   do_check_true(histogramsFile.exists());
   let mtime = histogramsFile.lastModifiedTime;
   histogramsFile.lastModifiedTime = mtime - (14 * 24 * 60 * 60 * 1000 + 60000); // 14 days, 1m
 
   yield TelemetryPing.testLoadHistograms(histogramsFile);
   do_check_false(histogramsFile.exists());
 });
 
-add_task(function* test_savedSessionClientID() {
-  // Assure that we store the ping properly when saving sessions on shutdown.
-  // We make the TelemetryPings shutdown to trigger a session save.
-  const dir = TelemetryFile.pingDirectoryPath;
-  yield OS.File.removeDir(dir, {ignoreAbsent: true});
-  yield OS.File.makeDir(dir);
-  TelemetryPing.shutdown();
-
-  yield TelemetryFile.loadSavedPings();
-  Assert.equal(TelemetryFile.pingsLoaded, 1);
-  let ping = TelemetryFile.popPendingPings().next();
-  Assert.equal(ping.value.payload.clientID, gDataReportingClientID);
-});
-
 add_task(function* stopServer(){
   gHttpServer.stop(do_test_finished);
 });
 
 // An iterable sequence of http requests
 function Request() {
   let defers = [];
   let current = 0;