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

chrome/browser/resources/pdf/pdf.js

Index: chrome/browser/resources/pdf/pdf.js
diff --git a/chrome/browser/resources/pdf/pdf.js b/chrome/browser/resources/pdf/pdf.js
index 18b008da3d6ddb7c2d8eca4ebca3dd4f575f5c38..0616c8df40ab1d66ea0ae1a68b962736a9fa4c32 100644
--- a/chrome/browser/resources/pdf/pdf.js
+++ b/chrome/browser/resources/pdf/pdf.js
@@ -235,14 +235,18 @@ PDFViewer.prototype = {
         }
         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;
     }
   },