[Mac] Change DomKey filter from 'non-printable' to 'non-control' characters

According to the latest spec we should filter non-glyph modifiers if the
produced characters are part of Unicode 'Other, Control' General Category.
e.g. http://www.fileformat.info/info/unicode/category/Cc/list.htm

This patch changes implementation to match spec and fixes issues on
'Dvorak - QWERTY Command' layout.

Spec: https://w3c.github.io/uievents-key/#selecting-key-attribute-values

Bug: 747358
Change-Id: I792b472132ea6deb4213206593136343a2050ccd
Reviewed-on: https://chromium-review.googlesource.com/585638Reviewed-by: Gary Kacmarcik <garykac@chromium.org>
Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Commit-Queue: Chong Zhang <chongz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491490}

content/browser/renderer_host/input/web_input_event_builders_mac_unittest.mm

@@ -379,6 +379,35 @@ TEST(WebInputEventBuilderMacTest, USDvorakAlnumNSEventToKeyCode) {
   }
 }
 
+// 'Dvorak - QWERTY Command' layout will map the key back to QWERTY when Command
+// is pressed.
+// e.g. Key 'b' maps to 'x' but 'Command-b' remains 'Command-b'.
+TEST(WebInputEventBuilderMacTest, USDvorakQWERTYCommand) {
+  struct DomKeyTestCase {
+    int mac_key_code;
+    unichar cmd_character;
+  } table[] = {{kVK_ANSI_0, '0'}, {kVK_ANSI_1, '1'}, {kVK_ANSI_2, '2'},
+               {kVK_ANSI_3, '3'}, {kVK_ANSI_4, '4'}, {kVK_ANSI_5, '5'},
+               {kVK_ANSI_6, '6'}, {kVK_ANSI_7, '7'}, {kVK_ANSI_8, '8'},
+               {kVK_ANSI_9, '9'}, {kVK_ANSI_A, 'a'}, {kVK_ANSI_B, 'b'},
+               {kVK_ANSI_C, 'c'}, {kVK_ANSI_D, 'd'}, {kVK_ANSI_E, 'e'},
+               {kVK_ANSI_F, 'f'}, {kVK_ANSI_G, 'g'}, {kVK_ANSI_H, 'h'},
+               {kVK_ANSI_I, 'i'}, {kVK_ANSI_J, 'j'}, {kVK_ANSI_K, 'k'},
+               {kVK_ANSI_L, 'l'}, {kVK_ANSI_M, 'm'}, {kVK_ANSI_N, 'n'},
+               {kVK_ANSI_O, 'o'}, {kVK_ANSI_P, 'p'}, {kVK_ANSI_Q, 'q'},
+               {kVK_ANSI_R, 'r'}, {kVK_ANSI_S, 's'}, {kVK_ANSI_T, 't'},
+               {kVK_ANSI_U, 'u'}, {kVK_ANSI_V, 'v'}, {kVK_ANSI_W, 'w'},
+               {kVK_ANSI_X, 'x'}, {kVK_ANSI_Y, 'y'}, {kVK_ANSI_Z, 'z'}};
+
+  for (const DomKeyTestCase& entry : table) {
+    NSEvent* mac_event = BuildFakeKeyEvent(
+        entry.mac_key_code, entry.cmd_character, NSCommandKeyMask, NSKeyDown);
+    WebKeyboardEvent web_event = WebKeyboardEventBuilder::Build(mac_event);
+    EXPECT_EQ(ui::DomKey::FromCharacter(entry.cmd_character),
+              web_event.dom_key);
+  }
+}
+
 // Test conversion from key combination with Control to DomKey.
 // TODO(chongz): Move DomKey tests for all platforms into one place.
 // http://crbug.com/587589

ui/events/keycodes/keyboard_code_conversion_mac.mm

@@ -18,6 +18,12 @@ namespace ui {
 
 namespace {
 
+bool IsUnicodeControl(unichar c) {
+  // C0 control characters: http://unicode.org/charts/PDF/U0000.pdf
+  // C1 control characters: http://unicode.org/charts/PDF/U0080.pdf
+  return c <= 0x1F || (c >= 0x7F && c <= 0x9F);
+}
+
 // This value is not defined but shows up as 0x36.
 const int kVK_RightCommand = 0x36;
 // Context menu is not defined but shows up as 0x6E.
@@ -850,18 +856,10 @@ DomKey DomKeyFromNSEvent(NSEvent* event) {
       // e.g. On French keyboard [+a will produce "^q", DomKey should be 'q'.
       unichar dom_key_char =
           [characters characterAtIndex:[characters length] - 1];
-      const bool is_ctrl_down = ([event modifierFlags] & NSControlKeyMask) &&
-                                !([event modifierFlags] & NSAlternateKeyMask);
-      const bool is_command_down = [event modifierFlags] & NSCommandKeyMask;
-      // On Mac Blink won't insert ASCII character if either Ctrl or Command, or
-      // both, are down.
-      // See EditingBehavior::shouldInsertCharacter()
-      if (std::iscntrl(dom_key_char) ||
-          (dom_key_char < 0x80 && (is_ctrl_down || is_command_down))) {
-        // According to spec if the key combination produces a non-printable
-        // character, the key value should be the character without modifiers
-        // except Shift and AltGr.
-        // See https://w3c.github.io/uievents/#keys-guidelines
+      if (IsUnicodeControl(dom_key_char)) {
+        // Filter non-glyph modifiers if the generated characters are part of
+        // Unicode 'Other, Control' General Category.
+        // https://w3c.github.io/uievents-key/#selecting-key-attribute-values
         bool unused_is_dead_key;
         const int kAllowedModifiersMask =
             NSShiftKeyMask | NSAlphaShiftKeyMask | NSAlternateKeyMask;
@@ -870,7 +868,10 @@ DomKey DomKeyFromNSEvent(NSEvent* event) {
             [event keyCode], [event modifierFlags] & kAllowedModifiersMask,
             &unused_is_dead_key);
       }
-      if (!std::iscntrl(dom_key_char))
+
+      // We need to check again because keys like ESC will produce control
+      // characters even without any modifiers.
+      if (!IsUnicodeControl(dom_key_char))
         return DomKeyFromCharCode(dom_key_char);
     }
   }