Gallery.app: Add shortcut keys for zooming in the slide mode.

ui/file_manager/gallery/js/slide_mode.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';
 
 /**
  * Slide mode displays a single image and has a set of controls to navigate
  * between the images and to edit an image.
  *
@@ skipping 316 matching lines @@
       this.dataModel_.removeEventListener('splice', this.onSpliceBound_);
       this.dataModel_.removeEventListener('content', this.onContentBound_);
       this.ribbon_.disable();
       this.active_ = false;
       if (this.savedSelection_)
         this.selectionModel_.selectedIndexes = this.savedSelection_;
       this.unloadImage_(zoomToRect);
       callback();
     }.bind(this);
 
+  this.viewport_.setZoomIndex(0);
   if (this.getItemCount_() === 0) {
     this.showErrorBanner_(false);
     commitDone();
   } else {
     this.commitItem_(commitDone);
   }
 
   // Disable the slide-mode only buttons when leaving.
   this.editButton_.setAttribute('disabled', '');
   this.printButton_.setAttribute('disabled', '');
@@ skipping 502 matching lines @@
     case 'End':
       this.selectLast();
       break;
     case 'Up':
     case 'Down':
     case 'Left':
     case 'Right':
       this.advanceWithKeyboard(keyID);
       break;
 
-    default: return false;
+    case 'Ctrl-U+00BB':  // Ctrl+'=' zoom in.
+      if (!this.isEditing()) {
+        this.viewport_.setZoomIndex(this.viewport_.getZoomIndex() + 1);
+        this.imageView_.draw();
+      }
+      break;
+
+    case 'Ctrl-U+00BD':  // Ctrl+'-' zoom out.
+      if (!this.isEditing()) {
+        this.viewport_.setZoomIndex(this.viewport_.getZoomIndex() - 1);
+        this.imageView_.draw();
+      }
+      break;
   }
 
   return true;
 };
 
 /**
  * Resize handler.
  * @private
  */
 SlideMode.prototype.onResize_ = function() {
@@ skipping 146 matching lines @@
 SlideMode.prototype.isSlideshowOn_ = function() {
   return this.container_.hasAttribute('slideshow');
 };
 
 /**
  * Start the slideshow.
  * @param {number=} opt_interval First interval in ms.
  * @param {Event=} opt_event Event.
  */
 SlideMode.prototype.startSlideshow = function(opt_interval, opt_event) {
+  // Reset zoom.
+  this.viewport_.setZoomIndex(0);
+  this.imageView_.draw();
+
   // Set the attribute early to prevent the toolbar from flashing when
   // the slideshow is being started from the mosaic view.
   this.container_.setAttribute('slideshow', 'playing');
 
   if (this.active_) {
     this.stopEditing_();
   } else {
     // We are in the Mosaic mode. Toggle the mode but remember to return.
     this.leaveAfterSlideshow_ = true;
     this.toggleMode_(this.startSlideshow.bind(
@@ skipping 131 matching lines @@
   if (!this.active_) {
     this.toggleMode_(this.toggleEditor.bind(this));
     return;
   }
 
   this.stopSlideshow_();
 
   ImageUtil.setAttribute(this.container_, 'editing', !this.isEditing());
 
   if (this.isEditing()) { // isEditing has just been flipped to a new value.
+    // Reset zoom.
+    this.viewport_.setZoomIndex(0);
+    this.imageView_.draw();
     if (this.context_.readonlyDirName) {
       this.editor_.getPrompt().showAt(
           'top', 'GALLERY_READONLY_WARNING', 0, this.context_.readonlyDirName);
     }
   } else {
     this.editor_.getPrompt().hide();
     this.editor_.leaveModeGently();
   }
 };
 
@@ skipping 76 matching lines @@
       done = true;
     }
   }.bind(this);
 };
 
 /**
  * If the user touched the image and moved the finger more than SWIPE_THRESHOLD
  * horizontally it's considered as a swipe gesture (change the current image).
  */
 SwipeOverlay.SWIPE_THRESHOLD = 100;