Remove GYP_GENERATORS=ninja code from android envsetup.

build/android/envsetup_functions.sh

Index: build/android/envsetup_functions.sh
diff --git a/build/android/envsetup_functions.sh b/build/android/envsetup_functions.sh
index 2c50cfed5a7de55c11c3484eebbbdee1bf999af8..176486d63bd0113ea3dcd3bb3faae29419944c5a 100755
--- a/build/android/envsetup_functions.sh
+++ b/build/android/envsetup_functions.sh
@@ -144,16 +144,6 @@ ${ANDROID_SDK_BUILD_TOOLS_VERSION}
 common_gyp_vars() {
   export GYP_DEFINES="${DEFINES}"
 
-  # Set GYP_GENERATORS to ninja if it's currently unset or null.
-  if [ -z "$GYP_GENERATORS" ]; then
-    echo "Defaulting GYP_GENERATORS to ninja."
-    GYP_GENERATORS=ninja
-  elif [ "$GYP_GENERATORS" != "ninja" ]; then
-    echo "Warning: GYP_GENERATORS set to '$GYP_GENERATORS'."
-    echo "Only GYP_GENERATORS=ninja has continuous coverage."
-  fi
-  export GYP_GENERATORS
-
   # Use our All target as the default
   export GYP_GENERATOR_FLAGS="${GYP_GENERATOR_FLAGS} default_target=All"