一、密码字段：
密码字段通过标签 <input type="password"> 来定义:
<form>
Password: <input type="password" name="pwd">
</form>二、password 对应c++定义：
third_party\blink\renderer\core\html\forms\password_input_type.h
third_party\blink\renderer\core\html\forms\password_input_type.cc
namespace blink {class KeyboardEvent;class PasswordInputType final : public BaseTextInputType {public:explicit PasswordInputType(HTMLInputElement& element): BaseTextInputType(Type::kPassword, element) {}private:void CountUsage() override;bool ShouldSaveAndRestoreFormControlState() const override;FormControlState SaveFormControlState() const override;void RestoreFormControlState(const FormControlState&) override;bool ShouldRespectListAttribute() override;bool NeedsContainer() const override;void CreateShadowSubtree() override;void UpdateView() override;void CapsLockStateMayHaveChanged() override;bool ShouldDrawCapsLockIndicator() const override;void UpdatePasswordRevealButton();void UpdateStrongPasswordLabel();void DidSetValueByUserEdit() override;void DidSetValue(const String&, bool value_changed) override;void ForwardEvent(Event& event) override;void HandleKeydownEvent(KeyboardEvent&) override;void HandleBeforeTextInsertedEvent(BeforeTextInsertedEvent&) override;void HandleBlurEvent() override;bool SupportsInputModeAttribute() const override;bool IsAutoDirectionalityFormAssociated() const override;bool should_draw_caps_lock_indicator_ = false;bool should_show_reveal_button_ = false;
};template <>
struct DowncastTraits<PasswordInputType> {static bool AllowFrom(const InputType& type) {return type.IsPasswordInputType();}
};} // namespace blink三、堆栈：
