Omnibox - Fix Rare HQP Crash

chrome/browser/autocomplete/history_quick_provider.cc

Index: chrome/browser/autocomplete/history_quick_provider.cc
diff --git a/chrome/browser/autocomplete/history_quick_provider.cc b/chrome/browser/autocomplete/history_quick_provider.cc
index 68cd805af91c950a9f5f13a6dfd9cf22509c1c02..1201efaa5a5f5bbd1608e96aa1ae6b1dba9796cb 100644
--- a/chrome/browser/autocomplete/history_quick_provider.cc
+++ b/chrome/browser/autocomplete/history_quick_provider.cc
@@ -257,20 +257,31 @@ AutocompleteMatch HistoryQuickProvider::QuickMatchToACMatch(
       SpansFromTermMatch(new_matches, match.contents.length(), true);
 
   // Set |inline_autocompletion| and |allowed_to_be_default_match| if possible.
+  // The second part of this test can happen if the only match(es) of the user's
+  // term occur in places FormatUrl() decides to omit in the formatted url.
+  // In these cases, it's impossible to set |inline_autocompletion| correctly
+  // and hence the match cannot be the default match.  I (mpearson@) do not
+  // know under what circumstances this can occur.
+  // See crbug.com/464926.
   if (history_match.can_inline) {
-    DCHECK(!new_matches.empty());
-    size_t inline_autocomplete_offset = new_matches[0].offset +
-        new_matches[0].length;
-    // |inline_autocomplete_offset| may be beyond the end of the
-    // |fill_into_edit| if the user has typed an URL with a scheme and the
-    // last character typed is a slash.  That slash is removed by the
-    // FormatURLWithOffsets call above.
-    if (inline_autocomplete_offset < match.fill_into_edit.length()) {
-      match.inline_autocompletion =
-          match.fill_into_edit.substr(inline_autocomplete_offset);
+    DCHECK(!new_matches.empty()) << "url=" << info.url().spec() << " input="
+        << autocomplete_input_.text() << " history_match.url_matches.size="
+        << history_match.url_matches.size() << " offsets.size="
+        << offsets.size();
+    if (!new_matches.empty()) {
+      size_t inline_autocomplete_offset = new_matches[0].offset +
+          new_matches[0].length;
+      // |inline_autocomplete_offset| may be beyond the end of the
+      // |fill_into_edit| if the user has typed an URL with a scheme and the
+      // last character typed is a slash.  That slash is removed by the
+      // FormatURLWithOffsets call above.
+      if (inline_autocomplete_offset < match.fill_into_edit.length()) {
+        match.inline_autocompletion =
+            match.fill_into_edit.substr(inline_autocomplete_offset);
+      }
+      match.allowed_to_be_default_match = match.inline_autocompletion.empty() ||
+          !PreventInlineAutocomplete(autocomplete_input_);
     }
-    match.allowed_to_be_default_match = match.inline_autocompletion.empty() ||
-        !PreventInlineAutocomplete(autocomplete_input_);
   }
   match.EnsureUWYTIsAllowedToBeDefault(
       autocomplete_input_.canonicalized_url(),