Do not show notifications when in fullscreen or screensaver mode....

chrome/browser/notifications/notification_ui_manager.cc

Index: chrome/browser/notifications/notification_ui_manager.cc
===================================================================
--- chrome/browser/notifications/notification_ui_manager.cc	(revision 72012)
+++ chrome/browser/notifications/notification_ui_manager.cc	(working copy)
@@ -8,6 +8,8 @@
 #include "base/scoped_ptr.h"
 #include "base/stl_util-inl.h"
 #include "chrome/browser/browser_process.h"
+#include "chrome/browser/fullscreen.h"
+#include "chrome/browser/idle.h"
 #include "chrome/browser/notifications/balloon_collection.h"
 #include "chrome/browser/notifications/notification.h"
 #include "chrome/browser/prefs/pref_service.h"
@@ -16,6 +18,10 @@
 #include "chrome/common/notification_type.h"
 #include "chrome/common/pref_names.h"
 
+namespace {
+const int kUserStatePollingIntervalSeconds = 1;
+}
+
 // A class which represents a notification waiting to be shown.
 class QueuedNotification {
  public:
@@ -42,14 +48,21 @@
 };
 
 NotificationUIManager::NotificationUIManager(PrefService* local_state)
-    : balloon_collection_(NULL) {
+    : balloon_collection_(NULL),
+      is_user_active_(true) {
   registrar_.Add(this, NotificationType::APP_TERMINATING,
                  NotificationService::AllSources());
   position_pref_.Init(prefs::kDesktopNotificationPosition, local_state, this);
+#if defined(OS_MACOSX)
+  InitMacFullScreenMonitor();
+#endif
 }
 
 NotificationUIManager::~NotificationUIManager() {
   STLDeleteElements(&show_queue_);
+#if defined(OS_MACOSX)
+  StopMacFullScreenMonitor();
+#endif
 }
 
 // static
@@ -126,10 +139,28 @@
 }
 
 void NotificationUIManager::CheckAndShowNotifications() {
-  // TODO(johnnyg): http://crbug.com/25061 - Check for user idle/presentation.
-  ShowNotifications();
+  CheckUserState();
+  if (is_user_active_)
+    ShowNotifications();
 }
 
+void NotificationUIManager::CheckUserState() {
+  bool is_user_active_previously = is_user_active_;
+  is_user_active_ = CalculateIdleState(0) != IDLE_STATE_LOCKED &&
+                    !IsFullScreenMode();

[evanm, 2011/01/21 00:42:05]

IsFullScreenMode, at least in the Linux implementation, will take a lot of time
to complete.

Is this on the UI thread?
If so, you're blocking the UI thread.
If not, you can't make UI calls from non-UI threads...

[jianli, 2011/01/21 01:15:50]

Yes, it is on UI thread. The Win32/MacOSX implementation should run quite fast.
For Linux, do you know any better way to do the detection? I can do a couple
following things to optimize the Linux experience:
1) Combine screensaver and fullscreen detection code so that we do not need to
call XQueryTree twice for each separate detection.
2) We can also cache the last user state from a very small period of time ago,
say 0.1s.

+  if (is_user_active_ == is_user_active_previously)
+    return;
+
+  if (is_user_active_) {
+    user_state_check_timer_.Stop();
+    ShowNotifications();

[John Gregg, 2011/01/21 07:14:51]

This doesn't look right at first glance because  CheckAndShowNotifications() is
already calling ShowNotifications().  Can you add a comment that this is
detecting (with the a timer) the first time that the user becomes active?  

[jianli, 2011/01/21 20:21:00]

Done.

+  } else if (!user_state_check_timer_.IsRunning()) {
+    user_state_check_timer_.Start(
+        base::TimeDelta::FromSeconds(kUserStatePollingIntervalSeconds), this,
+        &NotificationUIManager::CheckUserState);
+  }
+}
+
 void NotificationUIManager::ShowNotifications() {
   while (!show_queue_.empty() && balloon_collection_->HasSpace()) {
     scoped_ptr<QueuedNotification> queued_notification(show_queue_.front());