Fix for menus blocking user activity detection (Retry).

Original CL reverted here: https://codereview.chromium.org/998603003/

Menus used to block detecting user activity. The fix works by making the
UserActivityDetector a PlatformEventObserver rather than an
EventHandler.
Also made sure that PlatformEventSource has an instance in
ozone_platform_test.cc

TBR=oshima@chromium.org,jamescook@chromium.org
R=sadrul@chromium.org,alexst@chromium.org
BUG=462735
TEST=ui_base_unittests --gtest_filter=UserActivityDetectorTest.*

Review URL: https://codereview.chromium.org/1013003002

Cr-Commit-Position: refs/heads/master@{#321066}

1 files changed, 12 insertions, 1 deletions

diff --git a/ui/ozone/platform/test/ozone_platform_test.cc b/ui/ozone/platform/test/ozone_platform_test.cc
index fce3a9d..d94fde9 100644
--- a/ui/ozone/platform/test/ozone_platform_test.cc
+++ b/ui/ozone/platform/test/ozone_platform_test.cc
@@ -25,6 +25,17 @@ namespace ui {
 
 namespace {
 
+// A test implementation of PlatformEventSource that we can instantiate to make
+// sure that the PlatformEventSource has an instance while in unit tests.
+class TestPlatformEventSource : public ui::PlatformEventSource {
+ public:
+  TestPlatformEventSource() {}
+  ~TestPlatformEventSource() override {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TestPlatformEventSource);
+};
+
 // OzonePlatform for testing
 //
 // This platform dumps images to a file for testing purposes.
@@ -67,7 +78,7 @@ class OzonePlatformTest : public OzonePlatform {
     window_manager_->Initialize();
     // This unbreaks tests that create their own.
     if (!PlatformEventSource::GetInstance())
-      platform_event_source_ = PlatformEventSource::CreateDefault();
+      platform_event_source_.reset(new TestPlatformEventSource);
     KeyboardLayoutEngineManager::SetKeyboardLayoutEngine(
         make_scoped_ptr(new StubKeyboardLayoutEngine()));