Fix dependencies on mac in tools/BUILD.gn.

webrtc/tools/BUILD.gn

Index: webrtc/tools/BUILD.gn
diff --git a/webrtc/tools/BUILD.gn b/webrtc/tools/BUILD.gn
index 603e99944c612ca9d7fd1ed0ea5cfeea42dea400..c71d31d34bb3e655e4440dc95b1b2166f339cf68 100644
--- a/webrtc/tools/BUILD.gn
+++ b/webrtc/tools/BUILD.gn
@@ -47,6 +47,9 @@ executable("frame_analyzer") {
     ":command_line_parser",
     ":video_quality_analysis",
   ]
+  if (is_mac) {
+    libs = [ "Foundation.framework" ]
+  }
 }
 
 executable("rgba_to_i420_converter") {
@@ -59,6 +62,9 @@ executable("rgba_to_i420_converter") {
     ":command_line_parser",
     "../common_video",
   ]
+  if (is_mac) {
+    libs = [ "Foundation.framework" ]
+  }
 }
 
 # TODO(kjellander): Convert all of tools.gyp into GN here.
@@ -79,5 +85,8 @@ if (!build_with_chromium) {
       "../test:test_support_main",
       "//testing/gtest",
     ]
+    if (is_mac) {
+      libs = [ "Foundation.framework" ]
+    }
   }
 }