Teach PasswordAutofillAgent sometimes match prefixes of usernames

components/autofill/core/common/autofill_util_unittest.cc

Index: components/autofill/core/common/autofill_util_unittest.cc
diff --git a/components/autofill/core/common/autofill_util_unittest.cc b/components/autofill/core/common/autofill_util_unittest.cc
index 6e04dc76031f980e818546f76d3881012c25a7bc..67d9ddd80c8bba5ea841e71dd8299f8dec9ef586 100644
--- a/components/autofill/core/common/autofill_util_unittest.cc
+++ b/components/autofill/core/common/autofill_util_unittest.cc
@@ -14,22 +14,22 @@
 
 namespace autofill {
 
-// Tests for FieldIsSuggestionSubstringStartingOnTokenBoundary().
-struct FieldIsTokenBoundarySubstringCase {
+// Tests for IsSubstringStartingOnTokenBoundary().
+struct TokenBoundaryMatchersCase {
   const char* const field_suggestion;
   const char* const field_contents;
   const bool case_sensitive;
   const bool expected_result;
 };
 
-class FieldIsTokenBoundarySubstringCaseTest
-    : public testing::TestWithParam<FieldIsTokenBoundarySubstringCase> {};
+class SubstringStartingOnTokenBoundaryTest
+    : public testing::TestWithParam<TokenBoundaryMatchersCase> {};
 
-TEST_P(FieldIsTokenBoundarySubstringCaseTest,
-       FieldIsSuggestionSubstringStartingOnTokenBoundary) {
-  // FieldIsSuggestionSubstringStartingOnTokenBoundary should not work yet
+TEST_P(SubstringStartingOnTokenBoundaryTest,
+       IsSubstringStartingOnTokenBoundary) {
+  // IsSubstringStartingOnTokenBoundary should not work yet
   // without a flag.
-  EXPECT_FALSE(FieldIsSuggestionSubstringStartingOnTokenBoundary(
+  EXPECT_FALSE(IsSubstringStartingOnTokenBoundary(
       base::ASCIIToUTF16("ab@cd.b"), base::ASCIIToUTF16("b"), false));
 
   // Token matching is currently behind a flag.
@@ -43,7 +43,7 @@ TEST_P(FieldIsTokenBoundarySubstringCaseTest,
                << ", case_sensitive = " << test_case.case_sensitive);
 
   EXPECT_EQ(test_case.expected_result,
-            FieldIsSuggestionSubstringStartingOnTokenBoundary(
+            IsSubstringStartingOnTokenBoundary(
                 base::ASCIIToUTF16(test_case.field_suggestion),
                 base::ASCIIToUTF16(test_case.field_contents),
                 test_case.case_sensitive));
@@ -51,24 +51,60 @@ TEST_P(FieldIsTokenBoundarySubstringCaseTest,
 
 INSTANTIATE_TEST_CASE_P(
     AutofillUtilTest,
-    FieldIsTokenBoundarySubstringCaseTest,
-    testing::Values(
-        FieldIsTokenBoundarySubstringCase{"ab@cd.b", "a", false, true},
-        FieldIsTokenBoundarySubstringCase{"ab@cd.b", "b", false, true},
-        FieldIsTokenBoundarySubstringCase{"ab@cd.b", "Ab", false, true},
-        FieldIsTokenBoundarySubstringCase{"ab@cd.b", "Ab", true, false},
-        FieldIsTokenBoundarySubstringCase{"ab@cd.b", "cd", true, true},
-        FieldIsTokenBoundarySubstringCase{"ab@cd.b", "d", false, false},
-        FieldIsTokenBoundarySubstringCase{"ab@cd.b", "b@", true, false},
-        FieldIsTokenBoundarySubstringCase{"ab@cd.b", "ab", false, true},
-        FieldIsTokenBoundarySubstringCase{"ab@cd.b", "cd.b", true, true},
-        FieldIsTokenBoundarySubstringCase{"ab@cd.b", "b@cd", false, false},
-        FieldIsTokenBoundarySubstringCase{"ab@cd.b", "ab@c", false, true},
-        FieldIsTokenBoundarySubstringCase{"ba.a.ab", "a.a", false, true},
-        FieldIsTokenBoundarySubstringCase{"", "ab", false, false},
-        FieldIsTokenBoundarySubstringCase{"", "ab", true, false},
-        FieldIsTokenBoundarySubstringCase{"ab", "", false, true},
-        FieldIsTokenBoundarySubstringCase{"ab", "", true, true}));
+    SubstringStartingOnTokenBoundaryTest,
+    testing::Values(TokenBoundaryMatchersCase{"ab@cd.b", "a", false, true},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "b", false, true},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "Ab", false, true},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "Ab", true, false},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "cd", true, true},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "d", false, false},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "b@", true, false},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "ab", false, true},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "cd.b", true, true},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "b@cd", false, false},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "ab@c", false, true},
+                    TokenBoundaryMatchersCase{"ba.a.ab", "a.a", false, true},
+                    TokenBoundaryMatchersCase{"", "ab", false, false},
+                    TokenBoundaryMatchersCase{"", "ab", true, false},
+                    TokenBoundaryMatchersCase{"ab", "", false, true},
+                    TokenBoundaryMatchersCase{"ab", "", true, true}));
+
+class PrefixStartingOnTokenBoundaryTest
+    : public testing::TestWithParam<TokenBoundaryMatchersCase> {};
+
+TEST_P(PrefixStartingOnTokenBoundaryTest, IsPrefixStartingOnTokenBoundary) {
+  auto test_case = GetParam();
+  SCOPED_TRACE(testing::Message()
+               << "suggestion = " << test_case.field_suggestion
+               << ", contents = " << test_case.field_contents
+               << ", case_sensitive = " << test_case.case_sensitive);
+
+  EXPECT_EQ(test_case.expected_result,
+            IsPrefixStartingOnTokenBoundary(
+                base::ASCIIToUTF16(test_case.field_suggestion),
+                base::ASCIIToUTF16(test_case.field_contents),
+                test_case.case_sensitive));
+}
+
+INSTANTIATE_TEST_CASE_P(
+    AutofillUtilTest,
+    PrefixStartingOnTokenBoundaryTest,
+    testing::Values(TokenBoundaryMatchersCase{"ab@cd.b", "a", false, false},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "b", false, false},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "Ab", false, true},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "Ab", true, false},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "cd", true, false},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "d", false, false},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "b@", true, false},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "ab", false, true},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "cd.b", true, false},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "b@cd", false, false},
+                    TokenBoundaryMatchersCase{"ab@cd.b", "ab@c", false, false},
+                    TokenBoundaryMatchersCase{"ba.a.ab", "a.a", false, false},
+                    TokenBoundaryMatchersCase{"", "ab", false, false},
+                    TokenBoundaryMatchersCase{"", "ab", true, false},
+                    TokenBoundaryMatchersCase{"ab", "", false, false},
+                    TokenBoundaryMatchersCase{"ab", "", true, false}));
 
 // Tests for GetTextSelectionStart().
 struct GetTextSelectionStartCase {
@@ -84,8 +120,8 @@ class GetTextSelectionStartTest
 TEST_P(GetTextSelectionStartTest, GetTextSelectionStart) {
   auto test_case = GetParam();
   SCOPED_TRACE(testing::Message()
-               << "suggestion = " << test_case.field_suggestion
-               << ", contents = " << test_case.field_contents
+               << "full string = " << test_case.field_suggestion
+               << ", prefix = " << test_case.field_contents
                << ", case_sensitive = " << test_case.case_sensitive);
   EXPECT_EQ(
       test_case.expected_start,