Migrate HostZoomMap to live in StoragePartition.

content/browser/host_zoom_level_context.h

Index: content/browser/host_zoom_level_context.h
diff --git a/content/browser/host_zoom_level_context.h b/content/browser/host_zoom_level_context.h
new file mode 100644
index 0000000000000000000000000000000000000000..1a5456d106b4519b0a696bf7703a3b53db3ce2bd
--- /dev/null
+++ b/content/browser/host_zoom_level_context.h
@@ -0,0 +1,65 @@
+// Copyright (c) 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.
+
+#ifndef CONTENT_BROWSER_HOST_ZOOM_LEVEL_CONTEXT_H_
+#define CONTENT_BROWSER_HOST_ZOOM_LEVEL_CONTEXT_H_
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "content/browser/host_zoom_map_impl.h"
+#include "content/public/browser/zoom_level_prefs_store.h"
+
+class PrefService;
+
+namespace base {
+class FilePath;
+}
+
+namespace content {
+struct HostZoomLevelContextDeleter;
+
+// This class manages a HostZoomMap and, associates it with a PrefsStore,
+// if one is provided. It also serves to keep the zoom level machinery details
+// deparate from the owning StoragePartitionImpl.
+class HostZoomLevelContext
+    : public base::RefCountedThreadSafe<HostZoomLevelContext,
+                                        HostZoomLevelContextDeleter> {
+ public:
+  HostZoomLevelContext(scoped_ptr<ZoomLevelPrefsStore> zoom_level_prefs,
+                       const base::FilePath& file_path);
+
+  HostZoomMap* GetHostZoomMap() const { return host_zoom_map_impl_.get(); }
+  PrefService* GetZoomLevelPrefs() {
+    return zoom_level_prefs_ ? zoom_level_prefs_->GetPrefs() : NULL;
+  }
+
+ protected:
+  virtual ~HostZoomLevelContext();
+
+ private:
+  friend class base::DeleteHelper<HostZoomLevelContext>;
+  friend class base::RefCountedThreadSafe<HostZoomLevelContext,
+                                          HostZoomLevelContextDeleter>;
+  friend struct HostZoomLevelContextDeleter;
+
+  void DeleteOnCorrectThread() const;
+
+  scoped_ptr<HostZoomMapImpl> host_zoom_map_impl_;
+  // The prefs_store pointer needs to be released before the destructor for the
+  // HostZoomMapImpl is called, and so must be declared in this order.
+  scoped_ptr<ZoomLevelPrefsStore> zoom_level_prefs_;
+
+  DISALLOW_COPY_AND_ASSIGN(HostZoomLevelContext);
+};
+
+struct HostZoomLevelContextDeleter {
+  static void Destruct(const HostZoomLevelContext* context) {
+    context->DeleteOnCorrectThread();
+  }
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_HOST_ZOOM_LEVEL_CONTEXT_H_