Fixed extension sync-related crash in ChromeUrlRequestContext

Made ChromeUrlRequestContext handle multiple extension unloaded
notifications gracefully.

BUG=50567
TEST=manual (see repro in bug)

Review URL: http://codereview.chromium.org/2819072

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@54100 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/net/chrome_url_request_context.cc

@@ -841,8 +841,15 @@ void ChromeURLRequestContext::OnUnloadedExtension(const std::string& id) {
   if (is_off_the_record_)
     return;
   ExtensionInfoMap::iterator iter = extension_info_.find(id);
-  DCHECK(iter != extension_info_.end());
-  extension_info_.erase(iter);
+  if (iter != extension_info_.end()) {
+    extension_info_.erase(iter);
+  } else {
+    // NOTE: This can currently happen if we receive multiple unload
+    // notifications, e.g. setting incognito-enabled state for a
+    // disabled extension (e.g., via sync).  See
+    // http://code.google.com/p/chromium/issues/detail?id=50582 .
+    NOTREACHED() << id;
+  }
 }
 
 bool ChromeURLRequestContext::AreCookiesEnabled() const {