Revert of Use CopyOnWriteBuffer instead of Buffer to avoid unnecessary copies.

webrtc/base/copyonwritebuffer.h

Index: webrtc/base/copyonwritebuffer.h
diff --git a/webrtc/base/copyonwritebuffer.h b/webrtc/base/copyonwritebuffer.h
index 87f24bf51d6db78aecc44442c810d0d0887d8dec..17f2710f3ecbd404646268d4af9a003d7c2e5465 100644
--- a/webrtc/base/copyonwritebuffer.h
+++ b/webrtc/base/copyonwritebuffer.h
@@ -42,9 +42,7 @@
   template <typename T, typename internal::ByteType<T>::t = 0>
   CopyOnWriteBuffer(const T* data, size_t size, size_t capacity)
       : CopyOnWriteBuffer(size, capacity) {
-    if (buffer_) {
-      std::memcpy(buffer_->data(), data, size);
-    }
+    std::memcpy(buffer_->data(), data, size);
   }
 
   // Construct a buffer from the contents of an array.
@@ -125,24 +123,13 @@
     return !(*this == buf);
   }
 
-  uint8_t& operator[](size_t index) {
-    RTC_DCHECK_LT(index, size());
-    return data()[index];
-  }
-
-  uint8_t operator[](size_t index) const {
-    RTC_DCHECK_LT(index, size());
-    return cdata()[index];
-  }
-
   // Replace the contents of the buffer. Accepts the same types as the
   // constructors.
   template <typename T, typename internal::ByteType<T>::t = 0>
   void SetData(const T* data, size_t size) {
     RTC_DCHECK(IsConsistent());
     if (!buffer_ || !buffer_->HasOneRef()) {
-      buffer_ = size > 0 ? new RefCountedObject<Buffer>(data, size)
-                         : nullptr;
+      buffer_ = new RefCountedObject<Buffer>(data, size, size);
     } else {
       buffer_->SetData(data, size);
     }