Add a GN arg to include PartitionAlloc sources

base/BUILD.gn

 # Copyright (c) 2013 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.
 
 # HOW TO WRITE CONDITIONALS IN THIS FILE
 # ======================================
 #
 # In many other places, one would write a conditional that expresses all the
 # cases when a source file is used or unused, and then either add or subtract
 # it from the sources list in that case
@@ skipping 23 matching lines @@
 declare_args() {
   # Override this value to give a specific build date.
   # See //base/build_time.cc and //build/write_build_date_header.py for more
   # details and the expected format.
   override_build_date = "N/A"
 
   # Turn on memory profiling in the task profiler when the heap shim is
   # available, except for official builds for now.
   enable_memory_task_profiler =
       use_experimental_allocator_shim && (!is_official_build || is_syzyasan)
+
+  # Partition alloc is included by default except iOS.
+  use_partition_alloc = !is_ios
 }
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
 config("base_flags") {
   if (is_clang) {
     cflags = [
       # Don't die on dtoa code that uses a char as an array index.
@@ skipping 1174 matching lines @@
   } else {
     # Remove NaCl stuff.
     sources -= [
       "memory/shared_memory_nacl.cc",
       "os_compat_nacl.cc",
       "os_compat_nacl.h",
       "rand_util_nacl.cc",
       "synchronization/read_write_lock_nacl.cc",
     ]
 
-    if (!is_ios) {
+    if (use_partition_alloc) {
       # Add stuff that doesn't work in NaCl.
       sources += [
         # PartitionAlloc uses SpinLock, which doesn't work in NaCl (see below).
         "allocator/partition_allocator/address_space_randomization.cc",
         "allocator/partition_allocator/address_space_randomization.h",
         "allocator/partition_allocator/page_allocator.cc",
         "allocator/partition_allocator/page_allocator.h",
         "allocator/partition_allocator/partition_alloc.cc",
         "allocator/partition_allocator/partition_alloc.h",
       ]
@@ skipping 916 matching lines @@
     sources += [
       "mac/bind_objc_block_unittest.mm",
       "mac/foundation_util_unittest.mm",
       "mac/objc_property_releaser_unittest.mm",
       "mac/scoped_nsobject_unittest.mm",
       "strings/sys_string_conversions_mac_unittest.mm",
     ]
     set_sources_assignment_filter(sources_assignment_filter)
 
     # TODO(GYP): dep on copy_test_data_ios action.
-  } else {
+  }
+
+  if (use_partition_alloc) {
     sources += [ "allocator/partition_allocator/partition_alloc_unittest.cc" ]
   }
 
   if (is_mac) {
     libs = [
       "CoreFoundation.framework",
       "Foundation.framework",
     ]
   }
 
@@ skipping 371 matching lines @@
 }
 
 fuzzer_test("base_json_correctness_fuzzer") {
   sources = [
     "json/correctness_fuzzer.cc",
   ]
   deps = [
     ":base",
   ]
 }