[Mac] Force macOS confirm window to front after default browser change.

When you use Chrome's infobar or Settings page to make Chrome your
default browser, macOS presents a confirmation dialog. Sometimes macOS
orders the dialog onscreen but behind the browser window, where it is
effectively invisible. Without confirmation via this dialog, macOS will
not change your default browser.

This cl forces the UI element responsible for the dialog to become
active after setting the default browser, bringing the confirmation
dialog to the foreground, in front of all windows.

Bug: 775281
Change-Id: I5376d57c088ea6b564d84cb3d35442a4330f954b
Reviewed-on: https://chromium-review.googlesource.com/722221Reviewed-by: Mark Mentovai <mark@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Jayson Adams <shrike@chromium.org>
Cr-Commit-Position: refs/heads/master@{#509581}

chrome/browser/shell_integration_mac.mm

@@ -6,6 +6,7 @@
 
 #include "base/mac/bundle_locations.h"
 #include "base/mac/foundation_util.h"
+#include "base/mac/mac_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "chrome/common/channel_info.h"
 #include "components/version_info/version_info.h"
@@ -63,6 +64,26 @@ bool SetAsDefaultBrowser() {
     return false;
 
   [[NSWorkspace sharedWorkspace] setDefaultBrowserWithIdentifier:identifier];
+
+  // The CoreServicesUIAgent presents a dialog asking the user to confirm their
+  // new default browser choice, but the agent sometimes orders the dialog
+  // behind the Chrome window. The user never sees the dialog, and therefore
+  // never confirms the change. Make the CoreServicesUIAgent active so the
+  // confirmation dialog comes to the front.
+  if (base::mac::IsAtLeastOS10_10()) {
+    NSString* const kCoreServicesUIAgentBundleID =
+        @"com.apple.coreservices.uiagent";
+
+    for (NSRunningApplication* application in
+         [[NSWorkspace sharedWorkspace] runningApplications]) {
+      if ([[application bundleIdentifier]
+              isEqualToString:kCoreServicesUIAgentBundleID]) {
+        [application activateWithOptions:NSApplicationActivateAllWindows];
+        break;
+      }
+    }
+  }
+
   return true;
 }
 
@@ -152,4 +173,4 @@ DefaultWebClientState IsDefaultProtocolClient(const std::string& protocol) {
       IS_DEFAULT : NOT_DEFAULT;
 }
 
-}  // namespace shell_integration
+}  // namespace shell_integration
\ No newline at end of file