1 files changed, 48 insertions, 0 deletions
diff --git a/dom/geolocation/MLSFallback.h b/dom/geolocation/MLSFallback.h
new file mode 100644
index 0000000000..f0e7f75519
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+++ b/dom/geolocation/MLSFallback.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCOMPtr.h"
+#include "nsITimer.h"
+#include "nsINamed.h"
+
+class nsIGeolocationUpdate;
+class nsIGeolocationProvider;
+
+/*
+ This class wraps the NetworkGeolocationProvider in a delayed startup.
+ It is for providing a fallback to MLS when:
+ 1) using another provider as the primary provider, and
+ 2) that primary provider may fail to return a result (i.e. the error returned
+ is indeterminate, or no error callback occurs)
+
+ The intent is that the primary provider is started, then MLSFallback
+ is started with sufficient delay that the primary provider will respond first
+ if successful (in the majority of cases).
+
+ MLS has an average response of 3s, so with the 2s default delay, a response can
+ be expected in 5s.
+
+ Telemetry is recommended to monitor that the primary provider is responding
+ first when expected to do so.
+*/
+class MLSFallback : public nsITimerCallback, public nsINamed {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSITIMERCALLBACK
+  NS_DECL_NSINAMED
+
+  explicit MLSFallback(uint32_t delayMs = 2000);
+  nsresult Startup(nsIGeolocationUpdate* aWatcher);
+  nsresult Shutdown();
+
+ private:
+  nsresult CreateMLSFallbackProvider();
+  virtual ~MLSFallback();
+  nsCOMPtr<nsITimer> mHandoffTimer;
+  nsCOMPtr<nsIGeolocationProvider> mMLSFallbackProvider;
+  nsCOMPtr<nsIGeolocationUpdate> mUpdateWatcher;
+  const uint32_t mDelayMs;
+};