MacKeyboard: Don't generate keypress for non-printable char

content/browser/renderer_host/input/web_input_event_builders_mac.mm

 // Copyright 2015 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.
 
 /*
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2006-2009 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ skipping 99 matching lines @@
     case 62:  // Right Ctrl
       return IsModifierKeyUp([event modifierFlags], kRightControlKeyMask,
                              kLeftControlKeyMask, NSControlKeyMask);
 
     case 63:  // Function
       return ([event modifierFlags] & NSFunctionKeyMask) == 0;
   }
   return false;
 }
 
+inline NSString* FilterSpecialCharacter(NSString* str) {
+  if ([str length] != 1)
+    return str;
+  unichar c = [str characterAtIndex:0];
+  NSString* result = str;
+  if (c == 0x7F) {
+    // Backspace should be 8
+    result = @"\x8";
+  } else if (c >= 0xF700 && c <= 0xF7FF) {
+    // Mac private use characters should be @"\0" (@"" won't work)
+    // NSDeleteFunctionKey will also go into here
+    // Use the range 0xF700~0xF7FF to match
+    // http://www.opensource.apple.com/source/WebCore/WebCore-7601.1.55/platform/mac/KeyEventMac.mm
+    result = @"\0";
+  }
+  return result;
+}
+
 inline NSString* TextFromEvent(NSEvent* event) {
   if ([event type] == NSFlagsChanged)
     return @"";
-  return [event characters];
+  return FilterSpecialCharacter([event characters]);
 }
 
 inline NSString* UnmodifiedTextFromEvent(NSEvent* event) {
   if ([event type] == NSFlagsChanged)
     return @"";
-  return [event charactersIgnoringModifiers];
+  return FilterSpecialCharacter([event charactersIgnoringModifiers]);
 }
 
 NSString* KeyIdentifierForKeyEvent(NSEvent* event) {
   if ([event type] == NSFlagsChanged) {
     switch ([event keyCode]) {
       case 54:  // Right Command
       case 55:  // Left Command
         return @"Meta";
 
       case 57:  // Capslock
@@ skipping 467 matching lines @@
 
   // Begin Apple code, copied from KeyEventMac.mm
 
   // Always use 13 for Enter/Return -- we don't want to use AppKit's
   // different character for Enter.
   if (result.windowsKeyCode == '\r') {
     text_str = @"\r";
     unmodified_str = @"\r";
   }
 
-  // The adjustments below are only needed in backward compatibility mode,
-  // but we cannot tell what mode we are in from here.
-
-  // Turn 0x7F into 8, because backspace needs to always be 8.
-  if ([text_str isEqualToString:@"\x7F"])
-    text_str = @"\x8";
-  if ([unmodified_str isEqualToString:@"\x7F"])
-    unmodified_str = @"\x8";
   // Always use 9 for tab -- we don't want to use AppKit's different character
   // for shift-tab.
   if (result.windowsKeyCode == 9) {
     text_str = @"\x9";
     unmodified_str = @"\x9";
   }
 
   // End Apple code.
 
   if ([text_str length] < blink::WebKeyboardEvent::textLengthCap &&
@@ skipping 283 matching lines @@
       break;
     default:
       NOTIMPLEMENTED();
       result.type = blink::WebInputEvent::Undefined;
   }
 
   return result;
 }
 
 }  // namespace content