Speculative fix for a crash in AutofillPopupControllerImpl.

- AutofillPopupControllerImpl::UpdateDataListValues recreates all the view in
the dropdown.
- Later AutofillPopupControllerImpl::SetSelectedLine selects a new line and
passes the index of the previous one. It may not exist.

Bug: 965025
Change-Id: Ie53b521803dcf33b02602357bda39a30b5ba0f4d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1995392
Commit-Queue: Vasilii Sukhanov <vasilii@chromium.org>
Reviewed-by: Christos Froussios <cfroussios@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732366}

chrome/browser/ui/autofill/autofill_popup_controller_impl.cc

@@ -161,6 +161,7 @@ void AutofillPopupControllerImpl::UpdateDataListValues(
   DCHECK_EQ(suggestions_.size(), elided_values_.size());
   DCHECK_EQ(suggestions_.size(), elided_labels_.size());
 
+  selected_line_.reset();
   // Remove all the old data list values, which should always be at the top of
   // the list if they are present.
   while (!suggestions_.empty() &&

chrome/browser/ui/autofill/autofill_popup_controller_interactive_uitest.cc

@@ -6,7 +6,9 @@
 
 #include "base/macros.h"
 #include "build/build_config.h"
+#include "chrome/browser/ui/autofill/autofill_popup_controller_impl.h"
 #include "chrome/browser/ui/autofill/autofill_popup_view.h"
+#include "chrome/browser/ui/autofill/chrome_autofill_client.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_window.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
@@ -110,4 +112,30 @@ IN_PROC_BROWSER_TEST_F(AutofillPopupControllerBrowserTest,
   autofill_external_delegate_.reset();
 }
 
+// crbug.com/965025
+IN_PROC_BROWSER_TEST_F(AutofillPopupControllerBrowserTest, ResetSelectedLine) {
+  test::GenerateTestAutofillPopup(autofill_external_delegate_.get());
+
+  auto* client =
+      autofill::ChromeAutofillClient::FromWebContents(web_contents());
+  AutofillPopupController* controller =
+      client->popup_controller_for_testing().get();
+  ASSERT_TRUE(controller);
+
+  // Push some suggestions and select the line #3.
+  std::vector<base::string16> rows = {
+      base::ASCIIToUTF16("suggestion1"), base::ASCIIToUTF16("suggestion2"),
+      base::ASCIIToUTF16("suggestion3"), base::ASCIIToUTF16("suggestion4")};
+  client->UpdateAutofillPopupDataListValues(rows, rows);
+  controller->SetSelectedLine(3);
+
+  // Replace the list with the smaller one.
+  rows = {base::ASCIIToUTF16("suggestion1")};
+  client->UpdateAutofillPopupDataListValues(rows, rows);
+  // Make sure that previously selected line #3 doesn't exist.
+  ASSERT_LT(controller->GetLineCount(), 4);
+  // Selecting a new line should not crash.
+  controller->SetSelectedLine(0);
+}
+
 }  // namespace autofill