Add v8_os_page_size flag for cross compilation

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 47 matching lines @@
   v8_object_print = ""
 
   # With post mortem support enabled, metadata is embedded into libv8 that
   # describes various parameters of the VM for use by debuggers. See
   # tools/gen-postmortem-metadata.py for details.
   v8_postmortem_support = false
 
   # Switches off inlining in V8.
   v8_no_inline = false
 
+  # Override os page size when generating snapshot
+  target_os_page_size = "0"

[Michael Lippautz, 2016/11/14 09:24:43]

I'd make this v8_target_os_page_size. Not sure we need "target" in the name, as
we basically just override the os page size.

[Michael Achenbach, 2016/11/14 09:59:01]

Yes, please add a v8_ prefix. I don't care about the rest of the name, but we'd
like to know which args are from V8 in a chromium context.

+
   # Similar to vfp but on MIPS.
   v8_can_use_fpu_instructions = true
 
   # Similar to the ARM hard float ABI but on MIPS.
   v8_use_mips_abi_hardfloat = true
 }
 
 # Set project-specific defaults for some args if not provided in args.gn. The
 # defaults can be set in the respective build_overrides files.
 if (v8_imminent_deprecation_warnings == "") {
@@ skipping 586 matching lines @@
     rebase_path("$target_gen_dir/snapshot.cc", root_build_dir),
   ]
 
   if (v8_random_seed != "0") {
     args += [
       "--random-seed",
       v8_random_seed,
     ]
   }
 
+  if (target_os_page_size != "0") {
+    args += [
+      "--target_os_page_size",
+      target_os_page_size,
+    ]
+  }
+
   if (v8_use_external_startup_data) {
     outputs += [ "$root_out_dir/snapshot_blob.bin" ]
     args += [
       "--startup_blob",
       rebase_path("$root_out_dir/snapshot_blob.bin", root_build_dir),
     ]
   }
 
   if (v8_embed_script != "") {
     sources += [ v8_embed_script ]
@@ skipping 2298 matching lines @@
   ]
 
   configs = [
     ":external_config",
     ":internal_config_base",
   ]
 }
 
 v8_fuzzer("wasm_data_section_fuzzer") {
 }