[iOS/OSX] Refactor mac_framework so that it can be shared with iOS.

build/config/ios/rules.gni

Index: build/config/ios/rules.gni
diff --git a/build/config/ios/rules.gni b/build/config/ios/rules.gni
index 568cfadad1c60206441306a6c0edcf92e8731cae..604e7abec65b1ea63c80a47a95a254ea4864789b 100644
--- a/build/config/ios/rules.gni
+++ b/build/config/ios/rules.gni
@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import("//build/config/ios/ios_sdk.gni")
+import("//build/config/mac/rules.gni")
 
 # TODO(crbug.com/297668): refactor this template to extract common behaviour
 # between OS X and iOS bundle generation, then create a generic "app" template
@@ -31,7 +32,7 @@ import("//build/config/ios/ios_sdk.gni")
 #       by performing variable substitutions.
 #
 # For more information, see "gn help executable".
-template("app") {
+template("ios_app_bundle") {
   assert(defined(invoker.info_plist),
          "info_plist must be specified for target $target_name")
 
@@ -230,3 +231,25 @@ template("bundle_data_xib") {
     ]
   }
 }
+
+# Template to package a shared library into an iOS framework bundle.
+#
+# Arguments
+#
+#     output_name:
+#         (optional) string, name of the generated framework without the
+#         .framework suffix. If omitted, defaults to target_name.
+#
+#     framework_version:
+#         (optional) string, version of the framework. Typically this is a
+#         single letter, like "A". If omitted, the Versions/ subdirectory
+#         structure will not be created, and build output will go directly
+#         into the framework subdirectory.
+#
+# See "gn help shared_library" for more information on arguments supported
+# by shared library target.
+template("ios_framework_bundle") {
+  framework_bundle(target_name) {
+    forward_variables_from(invoker, "*")
+  }
+}