Don't recreate the speech encoder if we don't have to

webrtc/base/array_view.h

 /*
  *  Copyright 2015 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 38 matching lines @@
 //     }
 //     return false;
 //   }
 //
 // And even better, because a bunch of things will implicitly convert to
 // ArrayView, we can call it like this:
 //
 //   Contains17(arr);                             // C array
 //   Contains17(arr);                             // std::vector
 //   Contains17(rtc::ArrayView<int>(arr, size));  // pointer + size
+//   Contains17(nullptr);                         // nullptr -> empty ArrayView
 //   ...
 //
 // One important point is that ArrayView<T> and ArrayView<const T> are
 // different types, which allow and don't allow mutation of the array elements,
 // respectively. The implicit conversions work just like you'd hope, so that
 // e.g. vector<int> will convert to either ArrayView<int> or ArrayView<const
 // int>, but const vector<int> will convert only to ArrayView<const int>.
 // (ArrayView itself can be the source type in such conversions, so
 // ArrayView<int> will convert to ArrayView<const int>.)
 //
 // Note: ArrayView is tiny (just a pointer and a count) and trivially copyable,
 // so it's probably cheaper to pass it by value than by const reference.
 template <typename T>
 class ArrayView final {
  public:
   // Construct an empty ArrayView.
   ArrayView() : ArrayView(static_cast<T*>(nullptr), 0) {}
+  ArrayView(std::nullptr_t) : ArrayView() {}
 
   // Construct an ArrayView for a (pointer,size) pair.
   template <typename U>
   ArrayView(U* data, size_t size)
       : data_(size == 0 ? nullptr : data), size_(size) {
     CheckInvariant();
   }
 
   // Construct an ArrayView for an array.
   template <typename U, size_t N>
@@ skipping 38 matching lines @@
  private:
   // Invariant: !data_ iff size_ == 0.
   void CheckInvariant() const { RTC_DCHECK_EQ(!data_, size_ == 0); }
   T* data_;
   size_t size_;
 };
 
 }  // namespace rtc
 
 #endif  // WEBRTC_BASE_ARRAY_VIEW_H_