gfx: Rename canvas SaveAndUnscale to UnscaleTheDeviceScaleFactor.

ui/gfx/canvas.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 UI_GFX_CANVAS_H_
 #define UI_GFX_CANVAS_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 147 matching lines @@
                               SkColor halo_color,
                               const Rect& display_rect,
                               int flags);
 
   // Extracts an ImageSkiaRep from the contents of this canvas.
   ImageSkiaRep ExtractImageRep() const;
 
   // Draws a dashed rectangle of the specified color.
   void DrawDashedRect(const Rect& rect, SkColor color);
 
+  // Unscales by the image scale factor (aka device scale factor), and returns
+  // that factor.  This is useful when callers want to draw directly in the
+  // native scale.
+  float UnscaleTheDeviceScaleFactor();

[Peter Kasting, 2015/10/29 23:11:10]

This name is so verbose it reads poorly.  How about "UndoDeviceScale()", which
is admittedly slightly less accurate but seems clear enough and a lot less
wordy.

Or you could go in another direction and do "PrepareForPixelDrawing()" or the
like.

[sky, 2015/10/29 23:37:54]

+1 to Peter's first suggestion UndoDeviceScale.

[danakj, 2015/10/30 17:51:21]

Done. I used UndoDeviceScaleFactor(), because we never write just DeviceScale
(in code I've read), and often shorten to DSF in conversation etc.

+
   // Saves a copy of the drawing state onto a stack, operating on this copy
   // until a balanced call to Restore() is made.
   void Save();
 
-  // Saves the drawing state, unscales by the image scale factor, and returns
-  // that factor.  This is useful when callers want to draw directly in the
-  // native scale.
-  float SaveAndUnscale();
-
   // As with Save(), except draws to a layer that is blended with the canvas
   // at the specified alpha once Restore() is called.
   // |layer_bounds| are the bounds of the layer relative to the current
   // transform.
   void SaveLayerAlpha(uint8 alpha);
   void SaveLayerAlpha(uint8 alpha, const Rect& layer_bounds);
 
   // Restores the drawing state after a call to Save*(). It is an error to
   // call Restore() more times than Save*().
   void Restore();
@@ skipping 246 matching lines @@
 
   skia::RefPtr<skia::PlatformCanvas> owned_canvas_;
   SkCanvas* canvas_;
 
   DISALLOW_COPY_AND_ASSIGN(Canvas);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_CANVAS_H_