Adds the --enable-in-memory-url-index switch to gate creation and use of the InMemoryURLIndex.

BUG=19736
TEST=No change in behavior when flag is not used.  Should not crash when flag is used.
Review URL: http://codereview.chromium.org/2861041

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@51555 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 23 insertions, 3 deletions

diff --git a/chrome/browser/history/in_memory_history_backend.cc b/chrome/browser/history/in_memory_history_backend.cc
index d40c581..9f3e7be 100644
--- a/chrome/browser/history/in_memory_history_backend.cc
+++ b/chrome/browser/history/in_memory_history_backend.cc
@@ -1,13 +1,16 @@
-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 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 "chrome/browser/history/in_memory_history_backend.h"
 
+#include "base/command_line.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/history/history_notifications.h"
 #include "chrome/browser/history/in_memory_database.h"
+#include "chrome/browser/history/in_memory_url_index.h"
 #include "chrome/browser/profile.h"
+#include "chrome/common/chrome_switches.h"
 #include "chrome/common/notification_service.h"
 
 namespace history {
@@ -25,7 +28,15 @@ InMemoryHistoryBackend::~InMemoryHistoryBackend() {
 
 bool InMemoryHistoryBackend::Init(const FilePath& history_filename) {
   db_.reset(new InMemoryDatabase);
-  return db_->InitFromDisk(history_filename);
+  bool success = db_->InitFromDisk(history_filename);
+
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kEnableInMemoryURLIndex)) {
+    index_.reset(new InMemoryURLIndex);
+    // TODO(rohitrao): Load index.
+  }
+
+  return success;
 }
 
 void InMemoryHistoryBackend::AttachToHistoryService(Profile* profile) {
diff --git a/chrome/browser/history/in_memory_history_backend.h b/chrome/browser/history/in_memory_history_backend.h
index 18184bf..30026b5 100644
--- a/chrome/browser/history/in_memory_history_backend.h
+++ b/chrome/browser/history/in_memory_history_backend.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 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.
 
@@ -27,6 +27,7 @@ class Profile;
 namespace history {
 
 class InMemoryDatabase;
+class InMemoryURLIndex;
 struct URLsDeletedDetails;
 struct URLsModifiedDetails;
 
@@ -50,6 +51,12 @@ class InMemoryHistoryBackend : public NotificationObserver {
     return db_.get();
   }
 
+  // Returns the in memory index owned by this backend.  This index is only
+  // loaded when the --enable-in-memory-url-index flag is used.
+  InMemoryURLIndex* index() const {
+    return index_.get();
+  }
+
   // Notification callback.
   virtual void Observe(NotificationType type,
                        const NotificationSource& source,
@@ -68,6 +75,8 @@ class InMemoryHistoryBackend : public NotificationObserver {
 
   scoped_ptr<InMemoryDatabase> db_;
 
+  scoped_ptr<InMemoryURLIndex> index_;
+
   // The profile that this object is attached. May be NULL before
   // initialization.
   Profile* profile_;