[build] Conditionally print to stdout on Android

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("//build/config/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/dcheck_always_on.gni")
 import("//build/config/mips.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 
@@ skipping 65 matching lines @@
   }
 }
 if (v8_enable_gdbjit == "") {
   if (defined(v8_enable_gdbjit_default)) {
     v8_enable_gdbjit = v8_enable_gdbjit_default
   } else {
     v8_enable_gdbjit = false
   }
 }
 
+v8_standalone = defined(v8_standalone_build) && v8_standalone_build
 v8_generated_peephole_source = "$target_gen_dir/bytecode-peephole-table.cc"
 v8_random_seed = "314159265"
 v8_toolset_for_shell = "host"
 
 ###############################################################################
 # Configurations
 #
 config("internal_config") {
   visibility = [ ":*" ]  # Only targets in this file can depend on this.
 
@@ skipping 226 matching lines @@
       "VERIFY_HEAP",
       "DEBUG",
       "TRACE_MAPS",
     ]
     if (v8_enable_slow_dchecks) {
       defines += [ "ENABLE_SLOW_DCHECKS" ]
     }
   } else if (dcheck_always_on) {
     defines += [ "DEBUG" ]
   }
+
+  if (v8_standalone) {
+    if (is_android) {
+      defines += [ "V8_ANDROID_LOG_STDOUT" ]

[Michael Achenbach, 2016/07/26 15:06:34]

Porting
https://cs.chromium.org/chromium/src/v8/gypfiles/standalone.gypi?q=%22ANDROID...

See differences here:
https://build.chromium.org/p/client.v8.ports/builders/V8%20Android%20Arm%20-%...

The ANDROID define seems to come from chromium now, except for mksnapshot.cc

[vogelheim, 2016/07/27 07:43:40]

Are there any sort of asserts or unit tests for BUILD.gn files?

If this was in regular v8 code, this sort of built-in assumption that elsewhere
surely a flag had already been set and somewhere else entirely we intend rely on
its presence would make me super nervous, and I'd demand a rewrite or at least a
shitload of asserts. Does gn even give us the means to do that?

+    }
+  }
 }
 
 ###############################################################################
 # Actions
 #
 
 action("js2c") {
   visibility = [ ":*" ]  # Only targets in this file can depend on this.
 
   script = "tools/js2c.py"
@@ skipping 2169 matching lines @@
 
   deps = [
     ":fuzzer_support",
   ]
 
   configs = [ ":internal_config" ]
 }
 
 v8_fuzzer("wasm_asmjs_fuzzer") {
 }