Port ax_dump_tree tool on mac: implement application filtering by

pattern

Implement basic application pattern support which allows to indicate
which app to dump by its name. For example, --pattern=Safari or
--pattern="Sublime Text" will dump accessible tree for Safari or
Sublime Text applications accordingly.

Bug: 1124366
Change-Id: Ie2ee3868968d9f369aa208cc546af27ee1c6770f
AX-Relnotes: n/a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2404361Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Alexander Surkov <asurkov@igalia.com>
Cr-Commit-Position: refs/heads/master@{#807530}

content/browser/accessibility/accessibility_tree_formatter_mac.mm

@@ -170,7 +170,19 @@ AccessibilityTreeFormatterMac::BuildAccessibilityTreeForWindow(
 std::unique_ptr<base::DictionaryValue>
 AccessibilityTreeFormatterMac::BuildAccessibilityTreeForPattern(
     const base::StringPiece& pattern) {
-  NOTREACHED();
+  NSArray* windows = (NSArray*)CGWindowListCopyWindowInfo(
+      kCGWindowListOptionOnScreenOnly | kCGWindowListExcludeDesktopElements,
+      kCGNullWindowID);
+
+  for (NSDictionary* window_info in windows) {
+    NSString* window_name =
+        (NSString*)[window_info objectForKey:@"kCGWindowOwnerName"];
+    if (SysNSStringToUTF8(window_name) == pattern) {
+      NSNumber* pid =
+          (NSNumber*)[window_info objectForKey:@"kCGWindowOwnerPID"];
+      return BuildAccessibilityTreeForWindow([pid intValue]);
+    }
+  }
   return nullptr;
 }