gn2bp: Fix C++ warning showing up as errors when compiling cronet tests

Test: m
Change-Id: Id48dabf893fb7dc7698973f8d52a802134d77e82

tools/gn2bp/Android.bp.swp

@@ -4341,6 +4341,7 @@ cc_defaults {
     cflags: [
         "-DGOOGLE_PROTOBUF_NO_RTTI",
         "-Wno-ambiguous-reversed-operator",
+        "-Wno-c++11-narrowing",
         "-Wno-error=return-type",
         "-Wno-macro-redefined",
         "-Wno-missing-field-initializers",

tools/gn2bp/gen_android_bp

@@ -1673,6 +1673,7 @@ def create_blueprint_for_targets(gn, targets):
       '-Wno-ambiguous-reversed-operator', # needed for icui18n
       '-Wno-unreachable-code-loop-increment', # needed for icui18n
       '-fPIC',
+      '-Wno-c++11-narrowing',
   ]
   # Chromium builds do not add a dependency for headers found inside the
   # sysroot, so they are added globally via defaults.