PDF: Change the rotate shortcut keys to ctrl+[] on all platforms.

chrome/browser/resources/pdf/pdf.js

 // Copyright 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.
 
 'use strict';
 
 /**
  * @return {number} Width of a scrollbar in pixels
  */
 function getScrollbarWidth() {
@@ skipping 217 matching lines @@
         }
         return;
       case 80:  // p key.
         if (e.ctrlKey || e.metaKey) {
           this.print_();
           // Since we do the printing of the page.
           e.preventDefault();
         }
         return;
       case 219:  // left bracket.
-        this.plugin_.postMessage({
-          type: 'rotateCounterclockwise',
-        });
+        if (e.ctrlKey) {
+          this.plugin_.postMessage({
+            type: 'rotateCounterclockwise',
+          });
+        }
         return;
       case 221:  // right bracket.
-        this.plugin_.postMessage({
-          type: 'rotateClockwise',
-        });
+        if (e.ctrlKey) {
+          this.plugin_.postMessage({
+            type: 'rotateClockwise',
+          });
+        }
         return;
     }
   },
 
   /**
    * @private
    * Notify the plugin to print.
    */
   print_: function() {
     this.plugin_.postMessage({
@@ skipping 296 matching lines @@
     window.parent.postMessage(message, '*');
   },
 
   /**
    * @type {Viewport} the viewport of the PDF viewer.
    */
   get viewport() {
     return this.viewport_;
   }
 };