Separate building and enabling libevent.

webrtc/build/common.gypi

Index: webrtc/build/common.gypi
diff --git a/webrtc/build/common.gypi b/webrtc/build/common.gypi
index 4006d1745aabc7526b5ee111672d9220274765c3..9834ffc751ad5f34b16a6031c06443deffbbb856 100644
--- a/webrtc/build/common.gypi
+++ b/webrtc/build/common.gypi
@@ -19,9 +19,7 @@
 
           # Enable to use the Mozilla internal settings.
           'build_with_mozilla%': 0,
-          'build_for%': '',
         },
-        'build_for%': '<(build_for)',
         'build_with_chromium%': '<(build_with_chromium)',
         'build_with_mozilla%': '<(build_with_mozilla%)',
         'include_opus%': 1,
@@ -45,18 +43,21 @@
           }],
 
           # Controls whether we use libevent on posix platforms.
-          # TODO(tommi): Remove the 'build_for' condition once libevent is more
-          # widely available in posix configurations.
-          ['OS=="win" or OS=="mac" or OS=="ios" or build_for!=""', {
+          # TODO(phoglund): should arguably be controlled by platform #ifdefs
+          # in the code instead.
+          ['OS=="win" or OS=="mac" or OS=="ios"', {
             'build_libevent%': 0,
+            'enable_libevent%': 0,
           }, {
             'build_libevent%': 1,
+            'enable_libevent%': 1,
           }],
         ],
       },
       'build_with_chromium%': '<(build_with_chromium)',
       'build_with_mozilla%': '<(build_with_mozilla)',
       'build_libevent%': '<(build_libevent)',
+      'enable_libevent%': '<(enable_libevent)',
       'webrtc_root%': '<(webrtc_root)',
       'apk_tests_path%': '<(apk_tests_path)',
       'modules_java_gyp_path%': '<(modules_java_gyp_path)',
@@ -69,6 +70,7 @@
     'build_with_chromium%': '<(build_with_chromium)',
     'build_with_mozilla%': '<(build_with_mozilla)',
     'build_libevent%': '<(build_libevent)',
+    'enable_libevent%': '<(enable_libevent)',
     'webrtc_root%': '<(webrtc_root)',
     'apk_tests_path%': '<(apk_tests_path)',
     'test_runner_path': '<(DEPTH)/webrtc/build/android/test_runner.py',
@@ -332,11 +334,6 @@
           }],
         ],
       }],
-      ['build_libevent==1', {
-        'defines': [
-          'WEBRTC_BUILD_LIBEVENT',
-        ],
-      }],
       ['target_arch=="arm64"', {
         'defines': [
           'WEBRTC_ARCH_ARM64',