Implement disambiguation popup

content/renderer/disambiguation_popup_helper.h

+// 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.
+
+#ifndef CONTENT_RENDERER_DISAMBIGUATION_POPUP_HELPER_H_
+#define CONTENT_RENDERER_DISAMBIGUATION_POPUP_HELPER_H_
+
+#include "content/common/content_export.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebVector.h"
+
+namespace gfx {
+class Rect;
+class Size;
+}
+
+namespace WebKit {
+struct WebRect;
+}
+
+namespace content {
+
+// Contains functions to calculate proper scaling factor and popup size
+class DisambiguationPopupHelper {
+ public:
+  CONTENT_EXPORT static float ComputeZoomAreaAndScaleFactor(
+      const gfx::Rect& tap_rect,
+      const WebKit::WebVector<WebKit::WebRect>& target_rects,
+      const gfx::Size& viewport_size,
+      gfx::Rect* zoom_rect);
+};
+
+} // namespace content
+
+#endif // CONTENT_RENDERER_DISAMBIGUATION_POPUP_HELPER_H_