[android_webview] Hardcode the default text encoding to UTF-8.

android_webview/native/aw_resource.cc

Index: android_webview/native/aw_resource.cc
diff --git a/android_webview/native/aw_resource.cc b/android_webview/native/aw_resource.cc
index cf4b6f4ca1cc348d1d843719d7ac5317ba9c0cc9..498a201405495e3a68cb257750e9cdf009e31442 100644
--- a/android_webview/native/aw_resource.cc
+++ b/android_webview/native/aw_resource.cc
@@ -30,13 +30,6 @@ std::string GetNoDomainPageContent() {
   return base::android::ConvertJavaStringToUTF8(content);
 }
 
-std::string GetDefaultTextEncoding() {
-  JNIEnv* env = base::android::AttachCurrentThread();
-  ScopedJavaLocalRef<jstring> encoding =
-      Java_AwResource_getDefaultTextEncoding(env);
-  return base::android::ConvertJavaStringToUTF8(encoding);
-}
-
 bool RegisterAwResource(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }