Support target/host architecture with ninja iOS builds

base/base.gypi

Index: base/base.gypi
diff --git a/base/base.gypi b/base/base.gypi
index bdade596afd3d0369ba3796fe3e9e70d65887b4a..d88824ad001f43bc79d51c68b99831a00ad95ac7 100644
--- a/base/base.gypi
+++ b/base/base.gypi
@@ -672,7 +672,7 @@
               ['include', '^worker_pool_linux\\.cc$'],
             ],
           }],
-          ['OS == "ios"', {
+          ['OS == "ios" and _toolset != "host"', {
             'sources/': [
               # Pull in specific Mac files for iOS (which have been filtered out
               # by file name rules).
@@ -701,6 +701,15 @@
               'message_pump_libevent.cc'
             ],
           }],
+          ['OS == "ios" and _toolset == "host"', {
+            'sources/': [
+              # Copied filename_rules to switch from iOS to Mac inclusions.
+              ['include', '_(cocoa|mac)(_unittest)?\\.(h|cc|mm?)$'],
+              ['include', '(^|/)(cocoa|mac)/'],
+              ['exclude', '_ios(_unittest)?\\.(h|cc|mm?)$'],
+              ['exclude', '(^|/)ios/'],
+            ]
+          }],
           ['OS != "mac" or >(nacl_untrusted_build)==1', {
               'sources!': [
                 'mac/scoped_aedesc.h'