Allow view-source of pages fully-blocked by Blink's XSS filter.

chrome/browser/ui/browser_commands.cc

Index: chrome/browser/ui/browser_commands.cc
diff --git a/chrome/browser/ui/browser_commands.cc b/chrome/browser/ui/browser_commands.cc
index 8a593d55da12f375366a2edd253feb7f6b24ab29..74d6025469c49a7d5ff69ce2db3acf79f978e937 100644
--- a/chrome/browser/ui/browser_commands.cc
+++ b/chrome/browser/ui/browser_commands.cc
@@ -1148,6 +1148,17 @@ void ViewSource(Browser* browser, WebContents* contents) {
   if (!entry)
     return;
 
+  // The URL "data:," is a special case, since Blink uses it when it wants to
+  // show a "blocked page" from its reflected XSS filter. When the XSS filter
+  // triggers, the current entry gets marked as containing an XSS, and then a
+  // new navigation to "data:," occurs on top of it. Showing that page in place
+  // of the "data:," URL permits examination of the cause of the reflection.
+  if (entry->GetURL() == GURL("data:,")) {
+    NavigationEntry* previous = contents->GetController().GetEntryAtOffset(-1);
+    if (previous && previous->GetXssDetected())
+      entry = previous;
+  }
+
   ViewSource(browser, contents, entry->GetURL(), entry->GetPageState());
 }