Introduce a couple of abstract bases for WebDataService.

chrome/browser/api/webdata/web_data_results.h

Index: chrome/browser/api/webdata/web_data_results.h
diff --git a/chrome/browser/api/webdata/web_data_results.h b/chrome/browser/api/webdata/web_data_results.h
new file mode 100644
index 0000000000000000000000000000000000000000..6d2d5b8c34ccf62f4c335d93000aef13db952c32
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+++ b/chrome/browser/api/webdata/web_data_results.h
@@ -0,0 +1,89 @@
+// Copyright (c) 2012 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.
+
+#ifndef CHROME_BROWSER_API_WEBDATA_WEB_DATA_RESULTS_H_
+#define CHROME_BROWSER_API_WEBDATA_WEB_DATA_RESULTS_H_
+
+#include "base/basictypes.h"
+
+//
+// Result types for WebDataService.
+//
+typedef enum {
+  BOOL_RESULT = 1,             // WDResult<bool>
+  KEYWORDS_RESULT,             // WDResult<WDKeywordsResult>
+  INT64_RESULT,                // WDResult<int64>
+#if defined(OS_WIN)
+  PASSWORD_IE7_RESULT,         // WDResult<IE7PasswordInfo>
+#endif
+  WEB_APP_IMAGES,              // WDResult<WDAppImagesResult>
+  TOKEN_RESULT,                // WDResult<std::vector<std::string>>
+  AUTOFILL_VALUE_RESULT,       // WDResult<std::vector<string16>>
+  AUTOFILL_CHANGES,            // WDResult<std::vector<AutofillChange>>
+  AUTOFILL_PROFILE_RESULT,     // WDResult<AutofillProfile>
+  AUTOFILL_PROFILES_RESULT,    // WDResult<std::vector<AutofillProfile*>>
+  AUTOFILL_CREDITCARD_RESULT,  // WDResult<CreditCard>
+  AUTOFILL_CREDITCARDS_RESULT, // WDResult<std::vector<CreditCard*>>
+  WEB_INTENTS_RESULT,          // WDResult<std::vector<WebIntentServiceData>>
+  WEB_INTENTS_DEFAULTS_RESULT, // WDResult<std::vector<DefaultWebIntentService>>
+} WDResultType;
+
+//
+// The top level class for a result.
+//
+class WDTypedResult {
+ public:
+  virtual ~WDTypedResult() {}
+
+  // Return the result type.
+  WDResultType GetType() const {
+    return type_;
+  }
+
+ protected:
+  explicit WDTypedResult(WDResultType type) : type_(type) {
+  }
+
+ private:
+  WDResultType type_;
+  DISALLOW_COPY_AND_ASSIGN(WDTypedResult);
+};
+
+// A result containing one specific pointer or literal value.
+template <class T> class WDResult : public WDTypedResult {
+ public:
+
+  WDResult(WDResultType type, const T& v) : WDTypedResult(type), value_(v) {
+  }
+
+  virtual ~WDResult() {
+  }
+
+  // Return a single value result.
+  T GetValue() const {
+    return value_;
+  }
+
+ private:
+  T value_;
+
+  DISALLOW_COPY_AND_ASSIGN(WDResult);
+};
+
+template <class T> class WDObjectResult : public WDTypedResult {
+ public:
+  explicit WDObjectResult(WDResultType type) : WDTypedResult(type) {
+  }
+
+  T* GetValue() const {
+    return &value_;
+  }
+
+ private:
+  // mutable to keep GetValue() const.
+  mutable T value_;
+  DISALLOW_COPY_AND_ASSIGN(WDObjectResult);
+};
+
+#endif  // CHROME_BROWSER_API_WEBDATA_WEB_DATA_RESULTS_H_