Pass audio to AudioEncoder::Encode() in an ArrayView

webrtc/base/array_view.h

Index: webrtc/base/array_view.h
diff --git a/webrtc/base/array_view.h b/webrtc/base/array_view.h
index 019bd8b6c6b8f37f348f3d8a4d87f742f9602eba..02676f17d187cbcbbdbba41f3612c5b5ba72e4b4 100644
--- a/webrtc/base/array_view.h
+++ b/webrtc/base/array_view.h
@@ -61,6 +61,7 @@ class ArrayView final {
   // is const, because the ArrayView doesn't own the array. (To prevent
   // mutation, use ArrayView<const T>.)
   size_t size() const { return size_; }
+  bool empty() const { return size_ == 0; }
   T* data() const { return data_; }
   T& operator[](size_t idx) const {
     RTC_DCHECK_LT(idx, size_);
@@ -72,6 +73,15 @@ class ArrayView final {
   const T* cbegin() const { return data_; }
   const T* cend() const { return data_ + size_; }
 
+  // Comparing two ArrayViews compares their (pointer,size) pairs; it does
+  // *not* dereference the pointers.
+  friend bool operator==(const ArrayView& a, const ArrayView& b) {
+    return a.data_ == b.data_ && a.size_ == b.size_;
+  }
+  friend bool operator!=(const ArrayView& a, const ArrayView& b) {
+    return !(a == b);
+  }
+
  private:
   // Invariant: !data_ iff size_ == 0.
   void CheckInvariant() const { RTC_DCHECK_EQ(!data_, size_ == 0); }