Fix 26 ClangTidy - Readability findings in //depot/google3/third_party/quic/.

These fixes are automatically created by various analysis tools, but their application in this CL has been manually triggered.  See go/code-findings-fixes.

* redundant get() call on smart pointer (11 times)
* using decl 'Perspective' is unused
* using decl 'SETTINGS_MAX_HEADER_LIST_SIZE' is unused (2 times)
* using decl 'AtLeast' is unused
* using decl 'SpdySettingsIR' is unused
* using decl 'Pair' is unused
* using decl 'UnorderedElementsAre' is unused
* using decl 'Values' is unused
* using decl 'Combine' is unused
* using decl 'Invoke' is unused
* lambda capture 'this' is not used (4 times)
* using decl 'QuicSocketAddress' is unused

PiperOrigin-RevId: 276529025
Change-Id: Icee20b5bab6c9d8cc6c95b74594469257e791cb0

quic/core/crypto/crypto_handshake_message.cc

diff --git a/quic/core/crypto/crypto_handshake_message.cc b/quic/core/crypto/crypto_handshake_message.cc
index 022a86b..762a279 100644
--- a/quic/core/crypto/crypto_handshake_message.cc
+++ b/quic/core/crypto/crypto_handshake_message.cc
@@ -57,7 +57,7 @@
 }
 
 const QuicData& CryptoHandshakeMessage::GetSerialized() const {
-  if (!serialized_.get()) {
+  if (!serialized_) {
     serialized_ = CryptoFramer::ConstructHandshakeMessage(*this);
   }
   return *serialized_;