Return to suppressing deprecation warnings

BUILD.gn

 # Copyright 2014 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.
 
 import("//third_party/icu/config.gni")
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
@@ skipping 64 matching lines @@
       "/wd4267",  # Conversion from size_t on 64-bits.
       "/wd4333",  # Right shift by too large amount.
     ]
   } else if (is_linux || is_android) {
     cflags += [
       "-Wno-unused-function",
     ]
   }
   if (is_clang) {
     cflags += [
+      # ICU uses its own deprecated functions.
+      "-Wno-deprecated-declarations",
       # ICU has some code with the pattern:
       #   if (found = uprv_getWindowsTimeZoneInfo(...))
       "-Wno-parentheses",
       # ucnv2022.cpp contains three functions that are only used when
       # certain preprocessor defines are set.
       # unistr.cpp also has an unused function for non-component builds.
       "-Wno-unused-function",
     ]
   }
 }
@@ skipping 927 matching lines @@
       }
     }
 
     source_set("icudata") {
       sources = [ "$data_assembly" ]
       defines = [ "U_HIDE_DATA_SYMBOL" ]
       deps = [ ":make_data_assembly", ]
     }
   }
 }