Add notification (and unit test) for closing prefs window so it can be cleane...

chrome/app/nibs/en.lproj/Preferences.xib

Index: chrome/app/nibs/en.lproj/Preferences.xib
===================================================================
--- chrome/app/nibs/en.lproj/Preferences.xib	(revision 14958)
+++ chrome/app/nibs/en.lproj/Preferences.xib	(working copy)
@@ -2317,6 +2317,14 @@
 					</object>
 					<int key="connectionID">252</int>
 				</object>
+				<object class="IBConnectionRecord">
+					<object class="IBOutletConnection" key="connection">
+						<string key="label">delegate</string>
+						<reference key="source" ref="871378074"/>
+						<reference key="destination" ref="1001"/>
+					</object>
+					<int key="connectionID">253</int>
+				</object>
 			</object>
 			<object class="IBMutableOrderedSet" key="objectRecords">
 				<object class="NSArray" key="orderedObjects">
@@ -3789,7 +3797,7 @@
 				</object>
 			</object>
 			<nil key="sourceID"/>
-			<int key="maxID">252</int>
+			<int key="maxID">253</int>
 		</object>
 		<object class="IBClassDescriber" key="IBDocument.Classes">
 			<object class="NSMutableArray" key="referencedPartialClassDescriptions">