Merge changes Ia3ed3c1f,Ib802862d

* changes:
  gn2bp: Remove duplicated cflags from default.cflags
  gn2bp: Pass additional cflags to reduce cronet library size

tools/gn2bp/gen_android_bp

@@ -126,6 +126,20 @@ cflag_allowlist = [
   "-msse3",
   # needed for zlib:zlib
   "-msse4.2",
+  # flags to reduce binary size
+  "-O1",
+  "-O2",
+  "-O3",
+  "-Oz",
+  "-g1",
+  "-g2",
+  "-fdata-sections",
+  "-ffunction-sections",
+  "-fvisibility=hidden",
+  "-fvisibility-inlines-hidden",
+  "-fstack-protector",
+  "-mno-outline",
+  "-mno-outline-atomics"
 ]
 
 # Linker flags which are passed through to the blueprint.
@@ -1620,10 +1634,8 @@ def create_blueprint_for_targets(gn, targets):
       '-Wno-sign-promo',
       '-Wno-unused-parameter',
       '-Wno-null-pointer-subtraction', # Needed to libevent
-      '-fvisibility=hidden',
       '-Wno-ambiguous-reversed-operator', # needed for icui18n
       '-Wno-unreachable-code-loop-increment', # needed for icui18n
-      '-O2',
       '-fPIC',
   ]
   # Chromium builds do not add a dependency for headers found inside the