Make base work on iOS

base/debug/BUILD.gn

 # Copyright (c) 2015 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.
 
+if (is_android) {
+  import("//build/config/android/rules.gni")
+}
+
 source_set("debug") {
   sources = [
     "alias.cc",
     "alias.h",
     "asan_invalid_access.cc",
     "asan_invalid_access.h",
     "crash_logging.cc",
     "crash_logging.h",
     "debugger.cc",
     "debugger.h",
@@ skipping 22 matching lines @@
     "task_annotator.h",
   ]
 
   if (is_android) {
     # Android uses some Linux sources, put those back.
     set_sources_assignment_filter([])
     sources += [ "proc_maps_linux.cc" ]
     set_sources_assignment_filter(sources_assignment_filter)
 
     sources -= [ "stack_trace_posix.cc" ]
+
+    defines = [ "ANDROID_LOG_TAG=$android_log_tag" ]
   }
 
   if (is_nacl) {
     sources -= [
       "crash_logging.cc",
       "crash_logging.h",
       "stack_trace.cc",
       "stack_trace_posix.cc",
     ]
   }
@@ skipping 10 matching lines @@
     deps += [ "//base/third_party/symbolize" ]
   }
 
   allow_circular_includes_from = [
     "//base/memory",
     "//base/process",
   ]
 
   visibility = [ "//base/*" ]
 }