Port ax_dump_tree tool on mac: make ax_dump_tree tool get built on mac

Bug: 1124366
Change-Id: I79ba5caecabbdd825283d21f37b029bdc55d734f
AX-Relnotes: n/a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2390898
Commit-Queue: Alexander Surkov <asurkov@igalia.com>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@google.com>
Cr-Commit-Position: refs/heads/master@{#804407}

BUILD.gn

@@ -616,6 +616,9 @@ group("gn_all") {
     deps += [
       "//third_party/breakpad:crash_inspector",
       "//third_party/breakpad:dump_syms",
+
+      # The following are accessibility API tools.
+      "//tools/accessibility/inspect:ax_dump_tree",
     ]
     deps -= [
       # Mojo in GN contains some things which are never compiled in GYP on Mac,

tools/accessibility/inspect/README.md

@@ -14,16 +14,26 @@ Press Ctrl+C to quit.
 
 ## ax_dump_tree
 
-This tool helps monitor accessibility events. It currently works on Windows,
-and Mac is TBD.
+This tool helps to inspect accessibility trees of applications. Trees are dumped into console.
 
-Events are dumped to the console. To use it, run
-`ax_dump_events --window=[hwnd]`
+### Build
+
+`autoninja -C out/Default ax_dump_tree`
+
+### Run
+
+To dump accessibility tree of application, run
+`ax_dump_tree --window=id`
+where `id` is HWND on Windows, PID on Linux and Mac.
+
+Alternatively, you can indicate an application by its title:
+`ax_dump_tree --pattern=title`
 
 Notes:
 * To use a hex window handle prefix it with `0x`.
 * For json output, use the `--json` option
 * To filter certain properties, use `--filters=[path-to-filters.txt]` where the filters text file has a series of `@ALLOW` and/or `@DENY` lines. See example-tree-filters.txt in tools/accessibility/inspect.
+* [Mac] You have to turn on Accessibility for Terminal in Security & Privacy System Preferences.
 
 ## Convenience PowerShell scripts