[Mac] Fix "Chrome windows use more 'hidden' space on Exposé/Mission Control".

chrome/browser/ui/cocoa/status_bubble_mac.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/cocoa/status_bubble_mac.h"
 
 #include <limits>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 429 matching lines @@
       DCHECK_EQ([[window_ animator] alphaValue], 0.0);
       SetState(kBubbleHidden);
     }
   }
 }
 
 void StatusBubbleMac::SetState(StatusBubbleState state) {
   if (state == state_)
     return;
 
-  if (state == kBubbleHidden)
-    [window_ setFrame:NSMakeRect(0, 0, 1, 1) display:YES];
+  if (state == kBubbleHidden) {
+    // When hidden (with alpha of 0), make the window have the minimum size,
+    // while still keeping the same origin. It's important to not set the
+    // origin to 0,0 as that will cause the window to use more space in
+    // Expose/Mission Control. See http://crbug.com/81969.
+    //
+    // Also, doing it this way instead of detaching the window avoids bugs with
+    // Spaces and Cmd-`. See http://crbug.com/31821 and http://crbug.com/61629.
+    NSRect frame = [window_ frame];
+    frame.size = NSMakeSize(1, 1);
+    [window_ setFrame:frame display:YES];
+  }
 
   if ([delegate_ respondsToSelector:@selector(statusBubbleWillEnterState:)])
     [delegate_ statusBubbleWillEnterState:state];
 
   state_ = state;
 }
 
 void StatusBubbleMac::Fade(bool show) {
   DCHECK([NSThread isMainThread]);
 
@@ skipping 268 matching lines @@
     }
 
     // Round the top corners when the bubble is below the parent window.
     if (NSMinY(window_frame) < NSMinY(parent_frame)) {
       corner_flags |= kRoundedTopLeftCorner | kRoundedTopRightCorner;
     }
   }
 
   return corner_flags;
 }