Check the actual size of canvas to update.

ui/file_manager/gallery/js/image_editor/image_view.js

 // Copyright 2014 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.
 
 'use strict';
 
 /**
  * The overlay displaying the image.
  *
  * @param {HTMLElement} container The container element.
  * @param {Viewport} viewport The viewport.
  * @constructor
  * @extends {ImageBuffer.Overlay}
  */
 function ImageView(container, viewport) {
   ImageBuffer.Overlay.call(this);
 
   this.container_ = container;
   this.viewport_ = viewport;
   this.document_ = container.ownerDocument;
   this.contentGeneration_ = 0;
   this.displayedContentGeneration_ = 0;
-  this.displayedViewportGeneration_ = 0;
 
   this.imageLoader_ = new ImageUtil.ImageLoader(this.document_);
   // We have a separate image loader for prefetch which does not get cancelled
   // when the selection changes.
   this.prefetchLoader_ = new ImageUtil.ImageLoader(this.document_);
 
   // The content cache is used for prefetching the next image when going
   // through the images sequentially. The real life photos can be large
   // (18Mpix = 72Mb pixel array) so we want only the minimum amount of caching.
   this.contentCache_ = new ImageView.Cache(2);
@@ skipping 63 matching lines @@
 ImageView.prototype.getZIndex = function() { return -1; };
 
 /**
  * @override
  */
 ImageView.prototype.draw = function() {
   if (!this.contentCanvas_)  // Do nothing if the image content is not set.
     return;
 
   var forceRepaint = false;
-
-  if (this.displayedViewportGeneration_ !==
-      this.viewport_.getCacheGeneration()) {
-    this.displayedViewportGeneration_ = this.viewport_.getCacheGeneration();
-
+  var deviceBounds = this.viewport_.getDeviceBounds();
+  if (deviceBounds.width != this.screenImage_.width ||
+      deviceBounds.height != this.screenImage_.height) {
     this.setupDeviceBuffer(this.screenImage_);
-
     forceRepaint = true;
   }
 
   if (forceRepaint ||
       this.displayedContentGeneration_ !== this.contentGeneration_) {
     this.displayedContentGeneration_ = this.contentGeneration_;
-
     ImageUtil.trace.resetTimer('paint');
     this.paintDeviceRect(this.contentCanvas_, new Rect(this.contentCanvas_));
     ImageUtil.trace.reportTimer('paint');
   }
 };
 
 /**
  * Applies the viewport change that does not affect the screen cache size (zoom
  * change or offset change) with animation.
  */
@@ skipping 44 matching lines @@
 
 /**
  * Copies an image fragment from a full resolution canvas to a device resolution
  * canvas.
  *
  * @param {HTMLCanvasElement} canvas Canvas containing whole image. The canvas
  *     may not be full resolution (scaled).
  * @param {Rect} imageRect Rectangle region of the canvas to be rendered.
  */
 ImageView.prototype.paintDeviceRect = function(canvas, imageRect) {
-  // Check canvas size.
-  var deviceBounds = this.viewport_.getDeviceBounds();
-  if (this.screenImage_.width != deviceBounds.width ||
-      this.screenImage_.height != deviceBounds.height) {
-    console.error('The size of canvas is invalid.', (new Error).stack);
-    return;
-  }
-
   // Map the rectangle in full resolution image to the rectangle in the device
   // canvas.
+  var deviceBounds = this.viewport_.getDeviceBounds();
   var scaleX = deviceBounds.width / canvas.width;
   var scaleY = deviceBounds.height / canvas.height;
   var deviceRect = new Rect(
       imageRect.left * scaleX,
       imageRect.top * scaleY,
       imageRect.width * scaleX,
       imageRect.height * scaleY);
 
   Rect.drawImage(
       this.screenImage_.getContext('2d'), canvas, deviceRect, imageRect);
@@ skipping 761 matching lines @@
 };
 
 ImageView.Effect.Rotate.prototype = { __proto__: ImageView.Effect.prototype };
 
 /**
  * @override
  */
 ImageView.Effect.Rotate.prototype.transform = function(element, viewport) {
   return viewport.getInverseTransformForRotatedImage(this.orientation_);
 };