Plugs in the new thumbnailing algorithm to ThumbnailTabHelper.

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
index 41735606244fedc79215dfb521712e841efaed98..877a2eafee08afb0ba2d4508ca6ec48ed41d0ff8 100644
--- a/chrome/browser/thumbnails/thumbnailing_context.h
+++ b/chrome/browser/thumbnails/thumbnailing_context.h
@@ -10,6 +10,7 @@
 #include "chrome/browser/thumbnails/thumbnail_service.h"
 #include "chrome/common/thumbnail_score.h"
 #include "content/public/browser/web_contents.h"
+#include "ui/gfx/size.h"
 
 namespace thumbnails {
 
@@ -28,6 +29,8 @@ enum ClipResult {
   CLIP_RESULT_TALLER_THAN_WIDE,
   // The source and destination aspect ratios are identical.
   CLIP_RESULT_NOT_CLIPPED,
+  // The source and destination are identical.
+  CLIP_RESULT_SOURCE_SAME_AS_TARGET,
 };
 
 // Holds the information needed for processing a thumbnail.
@@ -36,13 +39,21 @@ struct ThumbnailingContext : base::RefCountedThreadSafe<ThumbnailingContext> {
                       ThumbnailService* receiving_service,
                       bool load_interrupted);
 
+  // Create an instance for use with unit tests.
+  static ThumbnailingContext* CreateThumbnailingContextForTest() {
+    return new ThumbnailingContext();
+  }
+
   scoped_refptr<ThumbnailService> service;
   GURL url;
   ClipResult clip_result;
+  gfx::Size requested_copy_size;
   ThumbnailScore score;
 
  private:
+  ThumbnailingContext();
   ~ThumbnailingContext();
+
   friend class base::RefCountedThreadSafe<ThumbnailingContext>;
 };