Remove third_party/quiche/common/platform/api/quiche_string_view.h.

I created this temporary workaround so that Abseil headers can be transitively
included in Chromium where they are banned.  I did this before I learned that a
much cleaner way to do this is to add an exception to a DEPS file.

PiperOrigin-RevId: 365887358
Change-Id: I75bf7df92b1a6dcdc59390604399436837d5d72f
diff --git a/common/platform/api/quiche_string_view.h b/common/platform/api/quiche_string_view.h
deleted file mode 100644
index 3fa7a21..0000000
--- a/common/platform/api/quiche_string_view.h
+++ /dev/null
@@ -1,18 +0,0 @@
-// Copyright 2021 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef QUICHE_COMMON_PLATFORM_API_QUICHE_STRING_VIEW_H_
-#define QUICHE_COMMON_PLATFORM_API_QUICHE_STRING_VIEW_H_
-
-// Chromium bans this include in net code except for QUICHE, which is a separate
-// compilation unit.  absl::string_view is used outside QUICHE in Chromium where
-// it is necessary to use the QUICHE API.  absl::Hash is used in
-// net/net/spdy/platform/impl/spdy_string_utils_impl.h in Chromium.  This header
-// file allows Chromium code to include string_view.h and hash.h where
-// absolutely necessary.
-
-#include "absl/hash/hash.h"
-#include "absl/strings/string_view.h"
-
-#endif  // QUICHE_COMMON_PLATFORM_API_QUICHE_STRING_VIEW_H_