Revert 152946 - Replace HistoryQuickProvider protobuf-based caching with an SQLite-based database.

chrome/browser/history/history_database.h

 // 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_HISTORY_HISTORY_DATABASE_H_
 #define CHROME_BROWSER_HISTORY_HISTORY_DATABASE_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
@@ skipping 131 matching lines @@
   // Query the segment ID for the provided visit. Return 0 on failure or if the
   // visit id wasn't found.
   SegmentID GetSegmentID(VisitID visit_id);
 
   // Retrieves/Updates early expiration threshold, which specifies the earliest
   // known point in history that may possibly to contain visits suitable for
   // early expiration (AUTO_SUBFRAMES).
   virtual base::Time GetEarlyExpirationThreshold();
   virtual void UpdateEarlyExpirationThreshold(base::Time threshold);
 
-  // Returns the database connection so that unit tests can directly access it.
-  sql::Connection* get_db_for_testing() { return &db_; }
-
  private:
 #if defined(OS_ANDROID)
   // AndroidProviderBackend uses the |db_|.
   friend class AndroidProviderBackend;
   FRIEND_TEST_ALL_PREFIXES(AndroidURLsMigrationTest, MigrateToVersion22);
 #endif
-  friend class InMemoryURLIndexBaseTest;
+  friend class InMemoryURLIndexTest;
   FRIEND_TEST_ALL_PREFIXES(IconMappingMigrationTest, TestIconMappingMigration);
 
   // Overridden from URLDatabase:
   virtual sql::Connection& GetDB() OVERRIDE;
 
   // Overridden from DownloadDatabase:
   virtual sql::MetaTable& GetMetaTable() OVERRIDE;
 
   // Migration -----------------------------------------------------------------
 
@@ skipping 21 matching lines @@
 
   // See the getters above.
   bool needs_version_17_migration_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryDatabase);
 };
 
 }  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_HISTORY_DATABASE_H_