Move QuicBufferAllocator into its own .cc/.h. No behavior change.

net/quic/core/quic_protocol.h

Index: net/quic/core/quic_protocol.h
diff --git a/net/quic/core/quic_protocol.h b/net/quic/core/quic_protocol.h
index 7d88cad679e162dff818b651a5a77b6b9fa60365..3b7e68d4698ee41b7bf9e7e659c7a6171b469c7c 100644
--- a/net/quic/core/quic_protocol.h
+++ b/net/quic/core/quic_protocol.h
@@ -29,6 +29,7 @@
 #include "net/base/net_export.h"
 #include "net/quic/core/interval_set.h"
 #include "net/quic/core/quic_bandwidth.h"
+#include "net/quic/core/quic_buffer_allocator.h"
 #include "net/quic/core/quic_constants.h"
 #include "net/quic/core/quic_time.h"
 #include "net/quic/core/quic_types.h"
@@ -563,26 +564,6 @@ struct NET_EXPORT_PRIVATE QuicPingFrame {};
 // frame.
 struct NET_EXPORT_PRIVATE QuicMtuDiscoveryFrame {};
 
-class NET_EXPORT_PRIVATE QuicBufferAllocator {
- public:
-  virtual ~QuicBufferAllocator();
-
-  // Returns or allocates a new buffer of |size|. Never returns null.
-  virtual char* New(size_t size) = 0;
-
-  // Returns or allocates a new buffer of |size| if |flag_enable| is true.
-  // Otherwise, returns a buffer that is compatible with this class directly
-  // with operator new. Never returns null.
-  virtual char* New(size_t size, bool flag_enable) = 0;
-
-  // Releases a buffer.
-  virtual void Delete(char* buffer) = 0;
-
-  // Marks the allocator as being idle. Serves as a hint to notify the allocator
-  // that it should release any resources it's still holding on to.
-  virtual void MarkAllocatorIdle() {}
-};
-
 // Deleter for stream buffers. Copyable to support platforms where the deleter
 // of a unique_ptr must be copyable. Otherwise it would be nice for this to be
 // move-only.