Make ConvertJavaToUTF functions more robusts.

base/android/jni_string.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/android/jni_string.h"
 
 #include "base/android/jni_android.h"
 #include "base/logging.h"
 #include "base/utf_string_conversions.h"
 
@@ skipping 30 matching lines @@
   // Further, Dalvik requires the string passed into NewStringUTF() to come from
   // a trusted source. We can't guarantee that all UTF8 will be sanitized before
   // it gets here, so constructing via UTF16 side-steps this issue.
   // (Dalvik stores strings internally as UTF16 anyway, so there shouldn't be
   // a significant performance hit by doing it this way).
   return ScopedJavaLocalRef<jstring>(env, ConvertUTF16ToJavaStringImpl(
       env, UTF8ToUTF16(str)));
 }
 
 string16 ConvertJavaStringToUTF16(JNIEnv* env, jstring str) {
+  if (!str) {
+    LOG(WARNING) << " ConvertJavaStringToUTF16 called with null string.";
+    return string16();
+  }
   const jchar* chars = env->GetStringChars(str, NULL);
   DCHECK(chars);
   // GetStringChars isn't required to NULL-terminate the strings
   // it returns, so the length must be explicitly checked.
   string16 result(chars, env->GetStringLength(str));
   env->ReleaseStringChars(str, chars);
   CheckException(env);
   return result;
 }
 
 string16 ConvertJavaStringToUTF16(const JavaRef<jstring>& str) {
   return ConvertJavaStringToUTF16(AttachCurrentThread(), str.obj());
 }
 
 ScopedJavaLocalRef<jstring> ConvertUTF16ToJavaString(
     JNIEnv* env,
     const base::StringPiece16& str) {
   return ScopedJavaLocalRef<jstring>(env,
                                      ConvertUTF16ToJavaStringImpl(env, str));
 }
 
 }  // namespace android
 }  // namespace base