Refactored-out the code of thumbnaling algorithm from thumbnail_tab_helper.

chrome/browser/thumbnails/thumbnailing_context.h

Index: chrome/browser/thumbnails/thumbnailing_context.h
diff --git a/chrome/browser/thumbnails/thumbnailing_context.h b/chrome/browser/thumbnails/thumbnailing_context.h
new file mode 100644
index 0000000000000000000000000000000000000000..41735606244fedc79215dfb521712e841efaed98
--- /dev/null
+++ b/chrome/browser/thumbnails/thumbnailing_context.h
@@ -0,0 +1,51 @@
+// Copyright (c) 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.
+
+#ifndef CHROME_BROWSER_THUMBNAILS_THUMBNAILING_CONTEXT_H_
+#define CHROME_BROWSER_THUMBNAILS_THUMBNAILING_CONTEXT_H_
+
+#include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+#include "chrome/browser/thumbnails/thumbnail_service.h"
+#include "chrome/common/thumbnail_score.h"
+#include "content/public/browser/web_contents.h"
+
+namespace thumbnails {
+
+// The result of clipping. This can be used to determine if the
+// generated thumbnail is good or not.
+enum ClipResult {
+  // Clipping is not done yet.
+  CLIP_RESULT_UNPROCESSED,
+  // The source image is smaller.
+  CLIP_RESULT_SOURCE_IS_SMALLER,
+  // Wider than tall by twice or more, clip horizontally.
+  CLIP_RESULT_MUCH_WIDER_THAN_TALL,
+  // Wider than tall, clip horizontally.
+  CLIP_RESULT_WIDER_THAN_TALL,
+  // Taller than wide, clip vertically.
+  CLIP_RESULT_TALLER_THAN_WIDE,
+  // The source and destination aspect ratios are identical.
+  CLIP_RESULT_NOT_CLIPPED,
+};
+
+// Holds the information needed for processing a thumbnail.
+struct ThumbnailingContext : base::RefCountedThreadSafe<ThumbnailingContext> {
+  ThumbnailingContext(content::WebContents* web_contents,
+                      ThumbnailService* receiving_service,
+                      bool load_interrupted);
+
+  scoped_refptr<ThumbnailService> service;
+  GURL url;
+  ClipResult clip_result;
+  ThumbnailScore score;
+
+ private:
+  ~ThumbnailingContext();
+  friend class base::RefCountedThreadSafe<ThumbnailingContext>;
+};
+
+}
+
+#endif  // CHROME_BROWSER_THUMBNAILS_THUMBNAILING_CONTEXT_H_