chrome: Fixes for Linux ChromiumOS ozone build

This fixes the path to event_rewriter_unittest.cc as well as adds a
missing dependency to chrome/browser/chromeos/BUILD.gn (already added to
GYP, forgot GN).

BUG=chromium:445627
TEST=gn gen out_gn_ozone --args='os="chromeos" use_ozone=true'
     (along with many other pending fixes)

Review URL: https://codereview.chromium.org/896033004

Cr-Commit-Position: refs/heads/master@{#314479}

chrome/browser/chromeos/BUILD.gn

@@ -110,6 +110,7 @@ source_set("chromeos") {
     "//ui/chromeos:ui_chromeos",
     "//ui/compositor",
     "//ui/display",
+    "//ui/events/devices",
     "//ui/events/platform",
     "//ui/events:dom4_keycode_converter",
     "//ui/file_manager",

chrome/test/BUILD.gn

@@ -1670,7 +1670,7 @@ if (!is_android && (!is_win || link_chrome_on_windows)) {
     }
     if (use_ozone) {
       # crbug.com/354036
-      sources -= [ "browser/chromeos/events/event_rewriter_unittest.cc" ]
+      sources -= [ "../browser/chromeos/events/event_rewriter_unittest.cc" ]
     }
     if (!enable_plugin_installation) {
       sources -= [ "../browser/plugins/plugin_installer_unittest.cc" ]