[Thumbnails] Specify copy size in Pixels, not DIPs

chrome/browser/thumbnails/simple_thumbnail_crop.h

 // 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_SIMPLE_THUMBNAIL_CROP_H_
 #define CHROME_BROWSER_THUMBNAILS_SIMPLE_THUMBNAIL_CROP_H_
 
 #include "chrome/browser/thumbnails/thumbnailing_algorithm.h"
 
 namespace thumbnails {
 
 // The implementation of the 'classic' thumbnail cropping algorithm. It is not
 // content-driven in any meaningful way (save for score calculation). Rather,
 // the choice of a cropping region is based on relation between source and
 // target sizes. The selected source region is then rescaled into the target
 // thumbnail image.
 class SimpleThumbnailCrop : public ThumbnailingAlgorithm {
  public:
   explicit SimpleThumbnailCrop(const gfx::Size& target_size);
 
   ClipResult GetCanvasCopyInfo(const gfx::Size& source_size,
                                ui::ScaleFactor scale_factor,
                                gfx::Rect* clipping_rect,
-                               gfx::Size* target_size) const override;
+                               gfx::Size* copy_size) const override;
 
   void ProcessBitmap(scoped_refptr<ThumbnailingContext> context,
                      const ConsumerCallback& callback,
                      const SkBitmap& bitmap) override;
 
   // Gets the clipped bitmap from |bitmap| per the aspect ratio of the
   // desired width and the desired height. For instance, if the input
   // bitmap is vertically long (ex. 400x900) and the desired size is
   // square (ex. 100x100), the clipped bitmap will be the top half of the
   // input bitmap (400x400).
   // Statically exposed for use by tests only.
   static SkBitmap GetClippedBitmap(const SkBitmap& bitmap,
                                    int desired_width,
                                    int desired_height,
                                    thumbnails::ClipResult* clip_result);
+  // Returns the size copied from the backing store. |thumbnail_size| is in
+  // DIP, returned size in pixels.
   static gfx::Size GetCopySizeForThumbnail(ui::ScaleFactor scale_factor,
                                            const gfx::Size& thumbnail_size);
   static gfx::Rect GetClippingRect(const gfx::Size& source_size,
                                    const gfx::Size& desired_size,
                                    ClipResult* clip_result);
 
   // Computes the size of a thumbnail that should be stored in the database from
   // |given_size| (expected to be the thumbnail size we would normally want to
   // see). The returned size is expressed in pixels and is determined by
   // bumping the resolution up to the maximum scale factor.
   static gfx::Size ComputeTargetSizeAtMaximumScale(const gfx::Size& given_size);
 
  protected:
   ~SimpleThumbnailCrop() override;
 
  private:
   static SkBitmap CreateThumbnail(const SkBitmap& bitmap,
                                   const gfx::Size& desired_size,
                                   ClipResult* clip_result);
 
+  // The target size of the captured thumbnails, in DIPs.
   const gfx::Size target_size_;
 
   DISALLOW_COPY_AND_ASSIGN(SimpleThumbnailCrop);
 };
 
 }  // namespace thumbnails
 
 #endif  // CHROME_BROWSER_THUMBNAILS_SIMPLE_THUMBNAIL_CROP_H_