Prepare for -Wall for third-party code, -Wextra for chromium_code

base/android/context_utils.cc

Index: base/android/context_utils.cc
diff --git a/base/android/context_utils.cc b/base/android/context_utils.cc
index 5e10f21842fc5e4dc2979173dfb9af248e90599e..fd62c45f606b28d4596283738e7d5eb6eed3d490 100644
--- a/base/android/context_utils.cc
+++ b/base/android/context_utils.cc
@@ -33,7 +33,7 @@ void SetNativeApplicationContext(JNIEnv* env, const JavaRef<jobject>& context) {
 
 }  // namespace
 
-const jobject GetApplicationContext() {
+jobject GetApplicationContext() {
   DCHECK(!g_application_context.Get().is_null());
   return g_application_context.Get().obj();
 }