PasswordReuseDetector implementation

components/password_manager/core/browser/password_reuse_detector.cc

Index: components/password_manager/core/browser/password_reuse_detector.cc
diff --git a/components/password_manager/core/browser/password_reuse_detector.cc b/components/password_manager/core/browser/password_reuse_detector.cc
new file mode 100644
index 0000000000000000000000000000000000000000..cde8904e2c84359ac1e7c074d0ae26992724f778
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+++ b/components/password_manager/core/browser/password_reuse_detector.cc
@@ -0,0 +1,62 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/password_manager/core/browser/password_reuse_detector.h"
+
+#include "components/autofill/core/common/password_form.h"
+#include "components/password_manager/core/browser/psl_matching_helper.h"
+
+namespace password_manager {
+
+namespace {
+// Minimum number of characters in a password for finding it as password reuse.
+// It does not make sense to consider short strings for password reuse, since it
+// is quite likely that they are parts of common words.
+constexpr size_t kMinPasswordLengthToCheck = 8;
+}
+
+PasswordReuseDetector::PasswordReuseDetector() {}
+
+PasswordReuseDetector::~PasswordReuseDetector() {}
+
+void PasswordReuseDetector::OnGetPasswordStoreResults(
+    std::vector<std::unique_ptr<autofill::PasswordForm>> results) {
+  passwords_.clear();
+  for (const auto& form : results) {
+    const base::string16& password = form->password_value;
+    if (password.size() < kMinPasswordLengthToCheck)
+      continue;
+    GURL signon_realm(form->signon_realm);
+    const std::string domain = GetRegistryControlledDomain(signon_realm);
+    passwords_[password].insert(domain);
+  }
+}
+
+void PasswordReuseDetector::CheckReuse(
+    const base::string16& input,
+    const std::string& domain,
+    PasswordReuseDetectorConsumer* consumer) {
+  // TODO(crbug.com/668155): Optimize password look-up.

[Nathan Parker, 2016/11/29 02:02:05]

Ah, nice. I read this bug and removed my optimization comments.  :-)

+  DCHECK(consumer);
+  const std::string registry_controlled_domain =
+      GetRegistryControlledDomain(GURL(domain));
+  for (size_t i = 0; i + kMinPasswordLengthToCheck <= input.size(); ++i) {
+    const base::string16 input_suffix = input.substr(i);
+    auto passwords_it = passwords_.find(input_suffix);
+    if (passwords_it == passwords_.end())
+      continue;
+
+    // Password found, check whether it's saved on the same domain.
+    const std::set<std::string>& domains = passwords_it->second;
+    DCHECK(!domains.empty());
+    if (domains.find(registry_controlled_domain) == domains.end()) {
+      // Return only one domain.
+      const std::string& saved_domain = *domains.begin();
+      consumer->OnReuseFound(input_suffix, saved_domain);
+      return;
+    }
+  }
+}
+
+}  // namespace password_manager