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

build/secondary/testing/gtest/BUILD.gn

Index: build/secondary/testing/gtest/BUILD.gn
diff --git a/build/secondary/testing/gtest/BUILD.gn b/build/secondary/testing/gtest/BUILD.gn
index 073faec56294fc03856b17d59c4b8745b69ded4a..a9f5007b2670a8619048c58e451396c26cc8f69f 100644
--- a/build/secondary/testing/gtest/BUILD.gn
+++ b/build/secondary/testing/gtest/BUILD.gn
@@ -96,12 +96,23 @@ static_library("gtest") {
     "src/gtest.cc",
   ]
 
-  if (is_mac) {
+  if (is_mac || is_ios) {
+    if (is_ios) {
+      set_sources_assignment_filter([])
+    }
     sources += [
       "../gtest_mac.h",
       "../gtest_mac.mm",
       "../platform_test_mac.mm",
     ]
+    set_sources_assignment_filter(sources_assignment_filter)
+  }
+
+  if (is_ios) {
+    sources += [
+      "../coverage_util_ios.cc",
+      "../coverage_util_ios.h",
+    ]
   }
 
   include_dirs = [ "." ]