"Go back" on the block interstitial closes the tab if there is no previous URL.

chrome/browser/managed_mode/managed_mode_interstitial.cc

Index: chrome/browser/managed_mode/managed_mode_interstitial.cc
diff --git a/chrome/browser/managed_mode/managed_mode_interstitial.cc b/chrome/browser/managed_mode/managed_mode_interstitial.cc
index 04dede1c3e74322fa7bb27c609560e072e194cc4..9d38abbe60ae47482ca417a96c3a2348079c12d0 100644
--- a/chrome/browser/managed_mode/managed_mode_interstitial.cc
+++ b/chrome/browser/managed_mode/managed_mode_interstitial.cc
@@ -208,6 +208,12 @@ void ManagedModeInterstitial::OnFilteringPrefsChanged() {
 }
 
 void ManagedModeInterstitial::DispatchContinueRequest(bool continue_request) {
+  // If there is no history entry to go back to, close the tab instead.
+  int nav_entry_count = web_contents_->GetController().GetEntryCount();
+  if (!continue_request && nav_entry_count == 0) {

[Bernhard Bauer, 2014/04/25 08:30:13]

Nit: braces are optional for one-line bodies in general, and in this file they
are left out.

[Marc Treib, 2014/04/25 08:50:34]

Done.

+    web_contents_->Close();
+  }
+
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE, base::Bind(callback_, continue_request));
 }