[iOS] Refactor iOS bots definitions.

ios/build/bots/chromium.mac/ios-simulator.json

Index: ios/build/bots/chromium.mac/ios-simulator.json
diff --git a/ios/build/bots/chromium.mac/ios-simulator.json b/ios/build/bots/chromium.mac/ios-simulator.json
index f32ce9d84040c34555cb7b734001a09533575a16..7b93100a871e925c5aea226142bd37539d577f39 100644
--- a/ios/build/bots/chromium.mac/ios-simulator.json
+++ b/ios/build/bots/chromium.mac/ios-simulator.json
@@ -1,10 +1,12 @@
 {
   "owners": [
+    "dpranke",
     "smut"
   ],
   "comments": [
     "Tests for 32- and 64-bit iOS 9.0 simulators.",
-    "Tests run on iPhone 5s (64-bit) and iPad Retina (32-bit)."
+    "Tests run on iPhone 5s (64-bit) and iPad Retina (32-bit).",
+    "Build is performed with gyp+ninja."
   ],
   "xcode version": "7.0",
   "GYP_DEFINES": [
@@ -15,8 +17,19 @@
     "gomadir=$(goma_dir)",
     "target_subarch=both"
   ],
+  "gn_args": [
+    "is_debug=true",
+    "target_os=\"ios\"",
+    "ios_enable_code_signing=false",
+    "is_component_build=false",
+    "use_goma=true",
+    "goma_dir=\"$(goma_dir)\"",
+    "target_cpu=\"x64\"",
+    "additional_target_cpus=[\"x86\"]"
+  ],
   "mb_type": "gyp",
   "compiler": "ninja",
+  "additional_compile_targets": ["gn_all"],
   "configuration": "Debug",
   "sdk": "iphonesimulator9.0",
   "tests": [