[Autofill/Autocomplete Feature] Substring matching instead of prefix matching.

components/password_manager/core/browser/password_autofill_manager_unittest.cc

Index: components/password_manager/core/browser/password_autofill_manager_unittest.cc
diff --git a/components/password_manager/core/browser/password_autofill_manager_unittest.cc b/components/password_manager/core/browser/password_autofill_manager_unittest.cc
index 7dd87dcebc16a8513abdebc3330c5c0e07825268..48daf6c5100867277ca5aaacb14e98920589b467 100644
--- a/components/password_manager/core/browser/password_autofill_manager_unittest.cc
+++ b/components/password_manager/core/browser/password_autofill_manager_unittest.cc
@@ -48,8 +48,10 @@ class MockPasswordManagerDriver : public StubPasswordManagerDriver {
  public:
   MOCK_METHOD2(FillSuggestion,
                void(const base::string16&, const base::string16&));
-  MOCK_METHOD2(PreviewSuggestion,
-               void(const base::string16&, const base::string16&));
+  MOCK_METHOD3(PreviewSuggestion,
+               void(const base::string16&,
+                    const base::string16&,
+                    size_t match_start));
 };
 
 class TestPasswordManagerClient : public StubPasswordManagerClient {
@@ -146,24 +148,25 @@ TEST_F(PasswordAutofillManagerTest, PreviewSuggestion) {
   scoped_ptr<TestPasswordManagerClient> client(new TestPasswordManagerClient);
   InitializePasswordAutofillManager(client.get(), nullptr);
 
+  size_t match_start = 0;
   EXPECT_CALL(*client->mock_driver(),
-              PreviewSuggestion(test_username_, test_password_));
+              PreviewSuggestion(test_username_, test_password_, match_start));
   EXPECT_TRUE(password_autofill_manager_->PreviewSuggestionForTest(
-      fill_data_id(), test_username_));
+      fill_data_id(), test_username_, match_start));
   testing::Mock::VerifyAndClearExpectations(client->mock_driver());
 
-  EXPECT_CALL(*client->mock_driver(), PreviewSuggestion(_, _)).Times(0);
+  EXPECT_CALL(*client->mock_driver(), PreviewSuggestion(_, _, _)).Times(0);
   EXPECT_FALSE(password_autofill_manager_->PreviewSuggestionForTest(
-      fill_data_id(), base::ASCIIToUTF16(kInvalidUsername)));
+      fill_data_id(), base::ASCIIToUTF16(kInvalidUsername), match_start));
 
   const int invalid_fill_data_id = fill_data_id() + 1;
 
   EXPECT_FALSE(password_autofill_manager_->PreviewSuggestionForTest(
-      invalid_fill_data_id, test_username_));
+      invalid_fill_data_id, test_username_, match_start));
 
   password_autofill_manager_->DidNavigateMainFrame();
   EXPECT_FALSE(password_autofill_manager_->PreviewSuggestionForTest(
-      fill_data_id(), test_username_));
+      fill_data_id(), test_username_, match_start));
 }
 
 // Test that the popup is marked as visible after recieving password