1 files changed, 42 insertions, 41 deletions

diff --git a/chromium/chrome/browser/resources/pdf/viewport_scroller.js b/chromium/chrome/browser/resources/pdf/viewport_scroller.js
index bb8c187d478..ca16c9cf7d2 100644
--- a/chromium/chrome/browser/resources/pdf/viewport_scroller.js
+++ b/chromium/chrome/browser/resources/pdf/viewport_scroller.js
@@ -5,75 +5,61 @@
 'use strict';
 
 /**
- * The period of time in milliseconds to wait between updating the viewport
- * position by the scroll velocity.
- *
- * @private
- */
-ViewportScroller.DRAG_TIMER_INTERVAL_MS_ = 100;
-
-/**
- * The maximum drag scroll distance per DRAG_TIMER_INTERVAL in pixels.
- *
- * @private
- */
-ViewportScroller.MAX_DRAG_SCROLL_DISTANCE_ = 100;
-
-/**
  * Creates a new ViewportScroller.
  * A ViewportScroller scrolls the page in response to drag selection with the
  * mouse.
  *
- * @param {Object} viewport The viewport info of the page.
- * @param {Object} plugin The PDF plugin element.
- * @param {Object} window The window containing the viewer.
- * @constructor
  */
-function ViewportScroller(viewport, plugin, window) {
-  this.viewport_ = viewport;
-  this.plugin_ = plugin;
-  this.window_ = window;
-  this.mousemoveCallback_ = null;
-  this.timerId_ = null;
-  this.scrollVelocity_ = null;
-  this.lastFrameTime_ = 0;
-}
+class ViewportScroller {
+  /**
+   * @param {Object} viewport The viewport info of the page.
+   * @param {Object} plugin The PDF plugin element.
+   * @param {Object} window The window containing the viewer.
+   */
+  constructor(viewport, plugin, window) {
+    this.viewport_ = viewport;
+    this.plugin_ = plugin;
+    this.window_ = window;
+    this.mousemoveCallback_ = null;
+    this.timerId_ = null;
+    this.scrollVelocity_ = null;
+    this.lastFrameTime_ = 0;
+  }
 
-ViewportScroller.prototype = {
   /**
    * Start scrolling the page by |scrollVelocity_| every
    * |DRAG_TIMER_INTERVAL_MS_|.
    *
    * @private
    */
-  startDragScrollTimer_: function() {
+  startDragScrollTimer_() {
     if (this.timerId_ === null) {
       this.timerId_ = this.window_.setInterval(
           this.dragScrollPage_.bind(this),
           ViewportScroller.DRAG_TIMER_INTERVAL_MS_);
       this.lastFrameTime_ = Date.now();
     }
-  },
+  }
 
   /**
    * Stops the drag scroll timer if it is active.
    *
    * @private
    */
-  stopDragScrollTimer_: function() {
+  stopDragScrollTimer_() {
     if (this.timerId_ !== null) {
       this.window_.clearInterval(this.timerId_);
       this.timerId_ = null;
       this.lastFrameTime_ = 0;
     }
-  },
+  }
 
   /**
    * Scrolls the viewport by the current scroll velocity.
    *
    * @private
    */
-  dragScrollPage_: function() {
+  dragScrollPage_() {
     const position = this.viewport_.position;
     const currentFrameTime = Date.now();
     const timeAdjustment = (currentFrameTime - this.lastFrameTime_) /
@@ -82,7 +68,7 @@ ViewportScroller.prototype = {
     position.x += (this.scrollVelocity_.x * timeAdjustment);
     this.viewport_.position = position;
     this.lastFrameTime_ = currentFrameTime;
-  },
+  }
 
   /**
    * Calculate the velocity to scroll while dragging using the distance of the
@@ -92,7 +78,7 @@ ViewportScroller.prototype = {
    * @return {Object} Object with x and y direction scroll velocity.
    * @private
    */
-  calculateVelocity_: function(event) {
+  calculateVelocity_(event) {
     const x =
         Math.min(
             Math.max(
@@ -106,7 +92,7 @@ ViewportScroller.prototype = {
             ViewportScroller.MAX_DRAG_SCROLL_DISTANCE_) *
         Math.sign(event.offsetY);
     return {x: x, y: y};
-  },
+  }
 
   /**
    * Handles mousemove events. It updates the scroll velocity and starts and
@@ -115,14 +101,14 @@ ViewportScroller.prototype = {
    * @param {Object} event The mousemove event.
    * @private
    */
-  onMousemove_: function(event) {
+  onMousemove_(event) {
     this.scrollVelocity_ = this.calculateVelocity_(event);
     if (!this.scrollVelocity_.x && !this.scrollVelocity_.y) {
       this.stopDragScrollTimer_();
     } else if (!this.timerId_) {
       this.startDragScrollTimer_();
     }
-  },
+  }
 
   /**
    * Sets whether to scroll the viewport when the mouse is outside the
@@ -130,7 +116,7 @@ ViewportScroller.prototype = {
    *
    * @param {boolean} isSelecting Represents selection status.
    */
-  setEnableScrolling: function(isSelecting) {
+  setEnableScrolling(isSelecting) {
     if (isSelecting) {
       if (!this.mousemoveCallback_) {
         this.mousemoveCallback_ = this.onMousemove_.bind(this);
@@ -145,4 +131,19 @@ ViewportScroller.prototype = {
       }
     }
   }
-};
+}
+
+/**
+ * The period of time in milliseconds to wait between updating the viewport
+ * position by the scroll velocity.
+ *
+ * @private
+ */
+ViewportScroller.DRAG_TIMER_INTERVAL_MS_ = 100;
+
+/**
+ * The maximum drag scroll distance per DRAG_TIMER_INTERVAL in pixels.
+ *
+ * @private
+ */
+ViewportScroller.MAX_DRAG_SCROLL_DISTANCE_ = 100;