Componentization: fix SupplementTracing<0>::~SupplementTracing<0>(void) already defined.

Source/core/page/PageSupplementable.h

Index: Source/core/page/PageSupplementable.h
diff --git a/Source/core/page/PageSupplementable.h b/Source/core/page/PageSupplementable.h
new file mode 100644
index 0000000000000000000000000000000000000000..abe36280df9e487c30323cde017f969a2c1d21b7
--- /dev/null
+++ b/Source/core/page/PageSupplementable.h
@@ -0,0 +1,20 @@
+// Copyright 2015 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 PageSupplementable_h
+#define PageSupplementable_h
+
+#include "core/CoreExport.h"
+#include "platform/Supplementable.h"
+
+namespace blink {
+
+class Page;
+
+extern template class CORE_TEMPLATE_EXPORT HeapSupplement<Page>;

[tasak, 2015/04/22 03:14:48]

Since both HeapSupplement<Page> and Supplement<Page> are used, need to add the
extern templates here (instead of 'extern template class CORE_TEMPLATE_EXPORT
WillBeHeapSupplement<Page>').

+extern template class CORE_TEMPLATE_EXPORT Supplement<Page>;

[tasak, 2015/04/22 03:14:48]

To fix the following link errors:
modules.dll.lib(modules.dll) : error LNK2005: "public: __cdecl
blink::Supplement<class blink::Page>::Supplement<class blink::Page>(void)"
(??0?$Supplement@VPage@blink@@@blink@@QEAA@XZ) already defined in
blink_web.StorageQuotaClientImpl.obj

modules.dll.lib(modules.dll) : error LNK2005: "public: virtual __cdecl
blink::Supplement<class blink::Page>::~Supplement<class blink::Page>(void)"
(??1?$Supplement@VPage@blink@@@blink@@UEAA@XZ) already defined in
blink_web.DatabaseClientImpl.obj

we should make core (not modules) to own Supplement<class blink::Page> (and also
HeapSupplement<class blink::Page>).
So we should explicitly say "extern template class __declspec(dllimport)
Supplement<Page>" for modules / web.
For core, "extern template class Supplement<Page>". Page.cpp instantiates the
class, i.e. template class Supplement<Page>.

+
+} // namespace blink
+
+#endif // PageSupplementable_h