diff --git a/net/BUILD.gn b/net/BUILD.gn
index 9d59189d80..dd5b6a0df3 100644
--- a/net/BUILD.gn
+++ b/net/BUILD.gn
@@ -2211,8 +2211,10 @@ component("net") {
         # Use ICU alternative on iOS.
         sources += [ "base/net_string_util_icu_alternatives_ios.mm" ]
       } else {
-        assert(false,
-               "ICU alternative is not implemented for platform: " + target_os)
+        sources += [
+          "base/filename_util_icu_dummy.cc",
+          "base/net_string_util_icu_alternatives_dummy.cc",
+        ]
       }
     } else {
       # Use ICU.
diff --git a/net/base/filename_util_icu_dummy.cc b/net/base/filename_util_icu_dummy.cc
new file mode 100644
index 0000000000..d67c8c9df3
--- /dev/null
+++ b/net/base/filename_util_icu_dummy.cc
@@ -0,0 +1,45 @@
+// Copyright 2014 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 "net/base/filename_util.h"
+
+#include "base/files/file_path.h"
+#include "base/logging.h"
+#include "base/strings/string16.h"
+
+class GURL;
+
+namespace net {
+
+bool IsSafePortablePathComponent(const base::FilePath& component) {
+  NOTIMPLEMENTED();
+  return false;
+}
+
+bool IsSafePortableRelativePath(const base::FilePath& path) {
+  NOTIMPLEMENTED();
+  return false;
+}
+
+base::string16 GetSuggestedFilename(const GURL& url,
+                                    const std::string& content_disposition,
+                                    const std::string& referrer_charset,
+                                    const std::string& suggested_name,
+                                    const std::string& mime_type,
+                                    const std::string& default_name) {
+  NOTIMPLEMENTED();
+  return base::string16();
+}
+
+base::FilePath GenerateFileName(const GURL& url,
+                                const std::string& content_disposition,
+                                const std::string& referrer_charset,
+                                const std::string& suggested_name,
+                                const std::string& mime_type,
+                                const std::string& default_file_name) {
+  NOTIMPLEMENTED();
+  return base::FilePath();
+}
+
+}  // namespace net
diff --git a/net/base/net_string_util_icu_alternatives_dummy.cc b/net/base/net_string_util_icu_alternatives_dummy.cc
new file mode 100644
index 0000000000..9e11876cd8
--- /dev/null
+++ b/net/base/net_string_util_icu_alternatives_dummy.cc
@@ -0,0 +1,43 @@
+// Copyright 2014 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 "net/base/net_string_util.h"
+
+#include "base/logging.h"
+
+namespace net {
+
+const char* const kCharsetLatin1 = "";
+
+bool ConvertToUtf8(const std::string& text, const char* charset,
+                   std::string* output) {
+  NOTIMPLEMENTED();
+  return false;
+}
+
+bool ConvertToUtf8AndNormalize(const std::string& text, const char* charset,
+                               std::string* output) {
+  NOTIMPLEMENTED();
+  return false;
+}
+
+bool ConvertToUTF16(const std::string& text, const char* charset,
+                    base::string16* output) {
+  NOTIMPLEMENTED();
+  return false;
+}
+
+bool ConvertToUTF16WithSubstitutions(const std::string& text,
+                                     const char* charset,
+                                     base::string16* output) {
+  NOTIMPLEMENTED();
+  return false;
+}
+
+bool ToUpper(const base::string16& str, base::string16* output) {
+  NOTIMPLEMENTED();
+  return false;
+}
+
+}  // namespace net
diff --git a/url/BUILD.gn b/url/BUILD.gn
index c4deb10db9..fd8fd02434 100644
--- a/url/BUILD.gn
+++ b/url/BUILD.gn
@@ -87,8 +87,7 @@ component("url") {
     } else if (is_ios) {
       sources += [ "url_canon_icu_alternatives_ios.mm" ]
     } else {
-      assert(false,
-             "ICU alternative is not implemented for platform: " + target_os)
+      sources += [ "url_canon_icu_alternatives_dummy.cc" ]
     }
   } else {
     # Use ICU.
diff --git a/url/url_canon_icu_alternatives_dummy.cc b/url/url_canon_icu_alternatives_dummy.cc
new file mode 100644
index 0000000000..ab439ee19a
--- /dev/null
+++ b/url/url_canon_icu_alternatives_dummy.cc
@@ -0,0 +1,15 @@
+// Copyright 2013 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/logging.h"
+#include "url/url_canon.h"
+
+namespace url {
+
+bool IDNToASCII(const base::char16* src, int src_len, CanonOutputW* output) {
+  NOTIMPLEMENTED();
+  return false;
+}
+
+}  // namespace url