diff --git a/hal/Hal.cpp b/hal/Hal.cpp
index f3646b3a9b3b..1528da069cb4 100644
--- a/hal/Hal.cpp
+++ b/hal/Hal.cpp
@@ -76,7 +76,7 @@ StaticAutoPtr<WindowIdentifier::IDArrayType> gLastIDToVibrate;
 
 static void RecordLastIDToVibrate(const WindowIdentifier& aId) {
   if (!InSandbox()) {
-    *gLastIDToVibrate = aId.AsArray();
+    *gLastIDToVibrate = aId.AsArray().Clone();
   }
 }
 
@@ -107,7 +107,7 @@ void Vibrate(const nsTArray<uint32_t>& pattern, nsPIDOMWindowInner* window) {
   Vibrate(pattern, WindowIdentifier(window));
 }
 
-void Vibrate(const nsTArray<uint32_t>& pattern, const WindowIdentifier& id) {
+void Vibrate(const nsTArray<uint32_t>& pattern, WindowIdentifier&& id) {
   AssertMainThread();
 
   // Only active windows may start vibrations.  If |id| hasn't gone
@@ -126,21 +126,23 @@ void Vibrate(const nsTArray<uint32_t>& pattern, const WindowIdentifier& id) {
   // Don't forward our ID if we are not in the sandbox, because hal_impl
   // doesn't need it, and we don't want it to be tempted to read it.  The
   // empty identifier will assert if it's used.
-  PROXY_IF_SANDBOXED(Vibrate(pattern, InSandbox() ? id : WindowIdentifier()));
+  PROXY_IF_SANDBOXED(
+      Vibrate(pattern, InSandbox() ? std::move(id) : WindowIdentifier()));
 }
 
 void CancelVibrate(nsPIDOMWindowInner* window) {
   CancelVibrate(WindowIdentifier(window));
 }
 
-void CancelVibrate(const WindowIdentifier& id) {
+void CancelVibrate(WindowIdentifier&& id) {
   AssertMainThread();
 
   if (MayCancelVibration(id)) {
     // Don't forward our ID if we are not in the sandbox, because hal_impl
     // doesn't need it, and we don't want it to be tempted to read it.  The
     // empty identifier will assert if it's used.
-    PROXY_IF_SANDBOXED(CancelVibrate(InSandbox() ? id : WindowIdentifier()));
+    PROXY_IF_SANDBOXED(
+        CancelVibrate(InSandbox() ? std::move(id) : WindowIdentifier()));
   }
 }
 
diff --git a/hal/Hal.h b/hal/Hal.h
index 560b1efc710d..d042658a0483 100644
--- a/hal/Hal.h
+++ b/hal/Hal.h
@@ -72,8 +72,7 @@ void Shutdown();
  * The method with WindowIdentifier will be called automatically.
  */
 void Vibrate(const nsTArray<uint32_t>& pattern, nsPIDOMWindowInner* aWindow);
-void Vibrate(const nsTArray<uint32_t>& pattern,
-             const hal::WindowIdentifier& id);
+void Vibrate(const nsTArray<uint32_t>& pattern, hal::WindowIdentifier&& id);
 
 /**
  * Cancel a vibration started by the content window identified by
@@ -88,7 +87,7 @@ void Vibrate(const nsTArray<uint32_t>& pattern,
  * automatically.
  */
 void CancelVibrate(nsPIDOMWindowInner* aWindow);
-void CancelVibrate(const hal::WindowIdentifier& id);
+void CancelVibrate(hal::WindowIdentifier&& id);
 
 #define MOZ_DEFINE_HAL_OBSERVER(name_)                             \
   /**                                                              \
diff --git a/hal/HalWakeLock.cpp b/hal/HalWakeLock.cpp
index efeb7fb8de7c..96c1cf364058 100644
--- a/hal/HalWakeLock.cpp
+++ b/hal/HalWakeLock.cpp
@@ -23,7 +23,7 @@ struct LockCount {
   LockCount() : numLocks(0), numHidden(0) {}
   uint32_t numLocks;
   uint32_t numHidden;
-  nsTArray<uint64_t> processes;
+  CopyableTArray<uint64_t> processes;
 };
 
 typedef nsDataHashtable<nsUint64HashKey, LockCount> ProcessLockTable;
diff --git a/hal/WindowIdentifier.cpp b/hal/WindowIdentifier.cpp
index 19a938aaf8ed..dc108016910f 100644
--- a/hal/WindowIdentifier.cpp
+++ b/hal/WindowIdentifier.cpp
@@ -12,22 +12,26 @@
 namespace mozilla {
 namespace hal {
 
-WindowIdentifier::WindowIdentifier() : mWindow(nullptr), mIsEmpty(true) {}
+WindowIdentifier::WindowIdentifier()
+    : mWindow(nullptr)
+#ifdef DEBUG
+      ,
+      mIsEmpty(true)
+#endif
+{
+}
 
 WindowIdentifier::WindowIdentifier(nsPIDOMWindowInner* window)
-    : mWindow(window), mIsEmpty(false) {
+    : mWindow(window) {
   mID.AppendElement(GetWindowID());
 }
 
-WindowIdentifier::WindowIdentifier(const nsTArray<uint64_t>& id,
+WindowIdentifier::WindowIdentifier(nsTArray<uint64_t>&& id,
                                    nsPIDOMWindowInner* window)
-    : mID(id), mWindow(window), mIsEmpty(false) {
+    : mID(std::move(id)), mWindow(window) {
   mID.AppendElement(GetWindowID());
 }
 
-WindowIdentifier::WindowIdentifier(const WindowIdentifier& other)
-    : mID(other.mID), mWindow(other.mWindow), mIsEmpty(other.mIsEmpty) {}
-
 const nsTArray<uint64_t>& WindowIdentifier::AsArray() const {
   MOZ_ASSERT(!mIsEmpty);
   return mID;
diff --git a/hal/WindowIdentifier.h b/hal/WindowIdentifier.h
index 34047b804936..11c5140f61b1 100644
--- a/hal/WindowIdentifier.h
+++ b/hal/WindowIdentifier.h
@@ -46,11 +46,6 @@ class WindowIdentifier {
    */
   WindowIdentifier();
 
-  /**
-   * Copy constructor.
-   */
-  WindowIdentifier(const WindowIdentifier& other);
-
   /**
    * Wrap the given window in a WindowIdentifier.  These two
    * constructors automatically grab the window's ID and append it to
@@ -66,7 +61,7 @@ class WindowIdentifier {
    * This automatically grabs the window's ID and appends it to the
    * array.
    */
-  WindowIdentifier(const nsTArray<uint64_t>& id, nsPIDOMWindowInner* window);
+  WindowIdentifier(nsTArray<uint64_t>&& id, nsPIDOMWindowInner* window);
 
   /**
    * Get the list of window and process IDs we contain.
@@ -100,7 +95,9 @@ class WindowIdentifier {
 
   AutoTArray<uint64_t, 3> mID;
   nsCOMPtr<nsPIDOMWindowInner> mWindow;
-  bool mIsEmpty;
+#ifdef DEBUG
+  bool mIsEmpty = false;
+#endif
 };
 
 }  // namespace hal
diff --git a/hal/android/AndroidHal.cpp b/hal/android/AndroidHal.cpp
index 16dd4dd57ede..098fc9db5035 100644
--- a/hal/android/AndroidHal.cpp
+++ b/hal/android/AndroidHal.cpp
@@ -20,7 +20,7 @@ namespace java = mozilla::java;
 namespace mozilla {
 namespace hal_impl {
 
-void Vibrate(const nsTArray<uint32_t>& pattern, const WindowIdentifier&) {
+void Vibrate(const nsTArray<uint32_t>& pattern, WindowIdentifier&&) {
   // Ignore the WindowIdentifier parameter; it's here only because hal::Vibrate,
   // hal_sandbox::Vibrate, and hal_impl::Vibrate all must have the same
   // signature.
@@ -49,7 +49,7 @@ void Vibrate(const nsTArray<uint32_t>& pattern, const WindowIdentifier&) {
   b->Vibrate(pattern);
 }
 
-void CancelVibrate(const WindowIdentifier&) {
+void CancelVibrate(WindowIdentifier&&) {
   // Ignore WindowIdentifier parameter.
 
   java::GeckoAppShell::CancelVibrate();
diff --git a/hal/fallback/FallbackVibration.cpp b/hal/fallback/FallbackVibration.cpp
index 13db8a0a8a5d..f3b0302d03d9 100644
--- a/hal/fallback/FallbackVibration.cpp
+++ b/hal/fallback/FallbackVibration.cpp
@@ -11,9 +11,9 @@ using mozilla::hal::WindowIdentifier;
 namespace mozilla {
 namespace hal_impl {
 
-void Vibrate(const nsTArray<uint32_t>& pattern, const hal::WindowIdentifier&) {}
+void Vibrate(const nsTArray<uint32_t>& pattern, hal::WindowIdentifier&&) {}
 
-void CancelVibrate(const hal::WindowIdentifier&) {}
+void CancelVibrate(hal::WindowIdentifier&&) {}
 
 }  // namespace hal_impl
 }  // namespace mozilla
diff --git a/hal/sandbox/SandboxHal.cpp b/hal/sandbox/SandboxHal.cpp
index d3b55c123a78..2c82c6cdef24 100644
--- a/hal/sandbox/SandboxHal.cpp
+++ b/hal/sandbox/SandboxHal.cpp
@@ -36,21 +36,19 @@ static PHalChild* Hal() {
   return sHal;
 }
 
-void Vibrate(const nsTArray<uint32_t>& pattern, const WindowIdentifier& id) {
+void Vibrate(const nsTArray<uint32_t>& pattern, WindowIdentifier&& id) {
   HAL_LOG("Vibrate: Sending to parent process.");
 
-  AutoTArray<uint32_t, 8> p(pattern);
-
-  WindowIdentifier newID(id);
+  WindowIdentifier newID(std::move(id));
   newID.AppendProcessID();
-  Hal()->SendVibrate(p, newID.AsArray(),
+  Hal()->SendVibrate(pattern, newID.AsArray(),
                      BrowserChild::GetFrom(newID.GetWindow()));
 }
 
-void CancelVibrate(const WindowIdentifier& id) {
+void CancelVibrate(WindowIdentifier&& id) {
   HAL_LOG("CancelVibrate: Sending to parent process.");
 
-  WindowIdentifier newID(id);
+  WindowIdentifier newID(std::move(id));
   newID.AppendProcessID();
   Hal()->SendCancelVibrate(newID.AsArray(),
                            BrowserChild::GetFrom(newID.GetWindow()));
@@ -166,8 +164,7 @@ class HalParent : public PHalParent,
     nsCOMPtr<nsIDOMWindow> window =
       do_QueryInterface(browserParent->GetBrowserDOMWindow());
     */
-    WindowIdentifier newID(id, nullptr);
-    hal::Vibrate(pattern, newID);
+    hal::Vibrate(pattern, WindowIdentifier(std::move(id), nullptr));
     return IPC_OK();
   }
 
@@ -178,8 +175,7 @@ class HalParent : public PHalParent,
     nsCOMPtr<nsIDOMWindow> window =
       browserParent->GetBrowserDOMWindow();
     */
-    WindowIdentifier newID(id, nullptr);
-    hal::CancelVibrate(newID);
+    hal::CancelVibrate(WindowIdentifier(std::move(id), nullptr));
     return IPC_OK();
   }