patch from chinmaygarde@ to make progress on mac, ios.

build/config/compiler/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.
 
 import("//build/config/android/config.gni")
 import("//build/config/chrome_build.gni")
 if (current_cpu == "arm") {
   import("//build/config/arm.gni")
 }
 if (current_cpu == "mipsel" || current_cpu == "mips64el") {
@@ skipping 248 matching lines @@
     if (current_cpu == "x64") {
       common_mac_flags += [
         "-arch",
         "x86_64",
       ]
     } else if (current_cpu == "x86") {
       common_mac_flags += [
         "-arch",
         "i386",
       ]
     } else if (current_cpu == "arm") {

[sdefresne, 2015/07/25 19:15:29]

I think we should add support for "armv7" and "arm64" cpu here too. Being able
to build for armv7 is useful when we have to debug issues that only happens on
non-64-bit devices (i.e. anything older than an iPhone 5s).

I would even go one step further and recommend removing support of "arm" as a
cpu as this is too ambiguous. There are three different ARM architecture that
are supported on iOS "armv7", "armv7s" and "arm64". Since we make the
distinction between "x86" and "x64" on Intel architecture even though "x64" cpu
can run "x86" code (the same as "arm64" do support "armv7" code), I think we
should do the same distinction for ARM architecture.

For webrtc, we can probably change their script to set target_cpu="arm64"
instead of target_cpu="arm".

[Dirk Pranke, 2015/07/31 21:27:40]

This seems reasonable but well out of the scope of what I want to do in this
patch. I'll add a TODO.

I would like to try and find names that work for both ios and android.

       common_mac_flags += [
         "-arch",
-        "armv7",
+        "arm64",
       ]
     }
 
     cflags += common_mac_flags
 
     # Without this, the constructors and destructors of a C++ object inside
     # an Objective C struct won't be called, which is very bad.
     cflags_objcc += [ "-fobjc-call-cxx-cdtors" ]
 
     cflags_c += [ "-std=c99" ]
@@ skipping 981 matching lines @@
       cflags += [ "-gsplit-dwarf" ]
     }
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }