For OSX, make it so that notifications only start resizing after the first paint is done.

chrome/browser/notifications/balloon.cc

Index: chrome/browser/notifications/balloon.cc
diff --git a/chrome/browser/notifications/balloon.cc b/chrome/browser/notifications/balloon.cc
index 96f3fca7b4f3668702e8d9df02ccae61252a1c04..ea12e4368c69cd9e47bee94e20243939f8847cc2 100644
--- a/chrome/browser/notifications/balloon.cc
+++ b/chrome/browser/notifications/balloon.cc
@@ -9,6 +9,7 @@
 #include "chrome/browser/notifications/notification.h"
 #include "chrome/browser/renderer_host/site_instance.h"
 #include "gfx/rect.h"
+#include "gfx/size.h"
 
 Balloon::Balloon(const Notification& notification, Profile* profile,
                  BalloonCollection* collection)
@@ -27,7 +28,18 @@ void Balloon::SetPosition(const gfx::Point& upper_left, bool reposition) {
 }
 
 void Balloon::SetContentPreferredSize(const gfx::Size& size) {
-  collection_->ResizeBalloon(this, size);
+  gfx::Size new_size(size);
+#if defined(OS_MACOSX)

[John Gregg, 2010/11/30 00:25:22]

add comment with a TODO and bug # about making this cross-platform

+  // Only allow the size of notifications to grow.  This stops the balloon
+  // from jumping between sizes due to dynamic content.  For example, the
+  // balloon's contents may adjust due to changes in
+  // document.body.clientHeight.
+  new_size.set_height(std::max(new_size.height(), content_size_.height()));
+
+  if (content_size_ == new_size)
+    return;
+#endif
+  collection_->ResizeBalloon(this, new_size);
 }
 
 void Balloon::set_view(BalloonView* balloon_view) {