[Mac Keyboard Accelerators] Disable Cmd = for M99

https://chromium-review.googlesource.com/c/chromium/src/+/3388332 adds
Cmd = as a hidden keyboard shortcut for Zoom In but does so in a way
that's not correct for non-US style keyboards. Disable Cmd = on
M99, in favor of a follow-up CL that will land in the near future.

This cl will need to be cherry-picked back to M99.

Bug: 1286243

Test: out/Release/unit_tests --gtest_filter=GlobalKeyboardShortcuts*
Change-Id: I343296c3ebdf9907250e4ad1d59938549e79a67c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3413662
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Jayson Adams <shrike@chromium.org>
Cr-Commit-Position: refs/heads/main@{#963606}

chrome/browser/global_keyboard_shortcuts_mac.mm

@@ -174,7 +174,6 @@ CommandForKeyEventResult ShortcutCommand(int cmd) {
     {true,  false, true,  false, kVK_ANSI_F,            IDC_FULLSCREEN},
 
     // Special shortcuts for Zoom in and out.
-    {true,  false, false, false, kVK_ANSI_Equal,        IDC_ZOOM_PLUS},
     {true,  false, false, false, kVK_ANSI_KeypadPlus,   IDC_ZOOM_PLUS},
     {true,  false, false, false, kVK_ANSI_KeypadMinus,  IDC_ZOOM_MINUS},
   });

chrome/browser/global_keyboard_shortcuts_mac_unittest.mm

@@ -174,7 +174,4 @@ int CommandForKeys(int vkey_code,
   const int cmdMinusFromKeypad =
       CommandForKeys(kVK_ANSI_KeypadMinus, CommandKeyState::kDown);
   EXPECT_EQ(cmdMinusFromKeypad, zoomOut);
-
-  const int cmdEquals = CommandForKeys(kVK_ANSI_Equal, CommandKeyState::kDown);
-  EXPECT_EQ(cmdEquals, zoomIn);
 }