Add deduplication logic to .pak files

ui/base/resource/data_pack_literal.h

Index: ui/base/resource/data_pack_literal.h
diff --git a/ui/base/resource/data_pack_literal.h b/ui/base/resource/data_pack_literal.h
new file mode 100644
index 0000000000000000000000000000000000000000..0e74647771d0354a516f56c3cdef07cdabe4df40
--- /dev/null
+++ b/ui/base/resource/data_pack_literal.h
@@ -0,0 +1,23 @@
+// Copyright 2017 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.
+
+#ifndef UI_BASE_RESOURCE_DATA_PACK_LITERAL_H_
+#define UI_BASE_RESOURCE_DATA_PACK_LITERAL_H_
+
+namespace ui {
+
+extern const char kSamplePakContentsV4[];
+extern const size_t kSamplePakSizeV4;
+extern const char kSamplePakContentsV5[];
+extern const size_t kSamplePakSizeV5;
+extern const char kSamplePakContents2x[];
+extern const size_t kSamplePakSize2x;
+extern const char kEmptyPakContents[];
+extern const size_t kEmptyPakSize;
+extern const char kSampleCorruptPakContents[];
+extern const size_t kSampleCorruptPakSize;
+
+}  // namespace ui
+
+#endif  // UI_BASE_RESOURCE_DATA_PACK_LITERAL_H_