Delete always-zero ByteBufferWriter::start_.

webrtc/base/bytebuffer.cc

Index: webrtc/base/bytebuffer.cc
diff --git a/webrtc/base/bytebuffer.cc b/webrtc/base/bytebuffer.cc
index c2ffe609341fbb74339d2c2101cfc298741bf342..317b6f383a564c904a1ea1d891b5cf90a38f2b6b 100644
--- a/webrtc/base/bytebuffer.cc
+++ b/webrtc/base/bytebuffer.cc
@@ -43,7 +43,6 @@ ByteBufferWriter::ByteBufferWriter(const char* bytes, size_t len,
 }
 
 void ByteBufferWriter::Construct(const char* bytes, size_t len) {
-  start_ = 0;
   size_ = len;
   bytes_ = new char[size_];
 
@@ -119,25 +118,21 @@ char* ByteBufferWriter::ReserveWriteBuffer(size_t len) {
 }
 
 void ByteBufferWriter::Resize(size_t size) {
-  size_t len = std::min(end_ - start_, size);
-  if (size <= size_) {
-    // Don't reallocate, just move data backwards
-    memmove(bytes_, bytes_ + start_, len);
-  } else {
+  size_t len = std::min(end_, size);
+  if (size > size_) {
     // Reallocate a larger buffer.
     size_ = std::max(size, 3 * size_ / 2);
     char* new_bytes = new char[size_];
-    memcpy(new_bytes, bytes_ + start_, len);
+    memcpy(new_bytes, bytes_, len);
     delete [] bytes_;
     bytes_ = new_bytes;
   }
-  start_ = 0;
   end_ = len;
 }
 
 void ByteBufferWriter::Clear() {
   memset(bytes_, 0, size_);
-  start_ = end_ = 0;
+  end_ = 0;
 }