[Mac][MC] Only show the status item when there are notifications in the tray.

This also cleans up the MCStatusItem interface to have a simple designated
initializer.

BUG=248319
TEST=No icon visible at launch. Show some notifications and the icon appears. Close the notifications in the tray and the icon disappears.
R=dewittj@chromium.org, thakis@chromium.org

Review URL: https://codereview.chromium.org/16836003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@206058 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 22 insertions, 16 deletions

diff --git a/ui/message_center/cocoa/status_item_view.h b/ui/message_center/cocoa/status_item_view.h
index f1f186a..29a26eb 100644
--- a/ui/message_center/cocoa/status_item_view.h
+++ b/ui/message_center/cocoa/status_item_view.h
@@ -47,9 +47,12 @@ MESSAGE_CENTER_EXPORT
 @property(nonatomic) size_t unreadCount;
 @property(nonatomic) BOOL highlight;
 
-// Designated initializer. This will take ownership of |item| and set self as
-// its view.
-- (id)initWithStatusItem:(NSStatusItem*)item;
+// Designated initializer. Creates a new NSStatusItem in the system menubar.
+- (id)init;
+
+// Removes the status item from the menubar. Must be called to break the
+// retain cycle between self and the NSStatusItem view.
+- (void)removeItem;
 
 @end
 
diff --git a/ui/message_center/cocoa/status_item_view.mm b/ui/message_center/cocoa/status_item_view.mm
index 4a76d931..085fa61 100644
--- a/ui/message_center/cocoa/status_item_view.mm
+++ b/ui/message_center/cocoa/status_item_view.mm
@@ -40,16 +40,23 @@ const CGFloat kUnreadCountMinY = 4;
 @synthesize unreadCount = unreadCount_;
 @synthesize highlight = highlight_;
 
-- (id)initWithStatusItem:(NSStatusItem*)item {
-  CGFloat thickness = [[item statusBar] thickness];
+- (id)init {
+  statusItem_.reset([[[NSStatusBar systemStatusBar] statusItemWithLength:
+      NSVariableStatusItemLength] retain]);
+  CGFloat thickness = [[statusItem_ statusBar] thickness];
+
   NSRect frame = NSMakeRect(0, 0, kStatusItemLength, thickness);
   if ((self = [super initWithFrame:frame])) {
-    statusItem_.reset([item retain]);
     [statusItem_ setView:self];
   }
   return self;
 }
 
+- (void)removeItem {
+  [[NSStatusBar systemStatusBar] removeStatusItem:statusItem_];
+  statusItem_.reset();
+}
+
 - (message_center::StatusItemClickedCallack)callback {
   return callback_.get();
 }
diff --git a/ui/message_center/cocoa/status_item_view_unittest.mm b/ui/message_center/cocoa/status_item_view_unittest.mm
index e276be1..7e9dc45 100644
--- a/ui/message_center/cocoa/status_item_view_unittest.mm
+++ b/ui/message_center/cocoa/status_item_view_unittest.mm
@@ -10,24 +10,20 @@
 class StatusItemViewTest : public ui::CocoaTest {
  public:
   StatusItemViewTest()
-      : status_item_([[NSStatusBar systemStatusBar] statusItemWithLength:
-                         NSVariableStatusItemLength]),
-        view_([[MCStatusItemView alloc] initWithStatusItem:status_item_]) {
+      : view_([[MCStatusItemView alloc] init]) {
   }
 
   virtual void SetUp() OVERRIDE {
-    // CocoaTest keeps a list of windows that were open at the time of its
-    // construction, and it will attempt to close all new ones. Using
-    // NSStatusBar creates a non-closeable window. Call Init() again after
-    // creating the NSStatusItem to exclude the status bar window from the
-    // list of windows to attempt to close.
-    ui::CocoaTest::Init();
     ui::CocoaTest::SetUp();
     [[test_window() contentView] addSubview:view_];
   }
 
+  virtual void TearDown() OVERRIDE {
+    [view_ removeItem];
+    ui::CocoaTest::TearDown();
+  }
+
  protected:
-  NSStatusItem* status_item_;  // Weak, owned by |view_|.
   scoped_nsobject<MCStatusItemView> view_;
 };