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

3 files changed, 50 insertions, 22 deletions

diff --git a/chrome/browser/autocomplete/history_url_provider.cc b/chrome/browser/autocomplete/history_url_provider.cc
index f1bd7f9..c3cc345 100644
--- a/chrome/browser/autocomplete/history_url_provider.cc
+++ b/chrome/browser/autocomplete/history_url_provider.cc
@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include "base/basictypes.h"
+#include "base/command_line.h"
 #include "base/histogram.h"
 #include "base/message_loop.h"
 #include "base/string_util.h"
@@ -17,6 +18,7 @@
 #include "chrome/browser/net/url_fixer_upper.h"
 #include "chrome/browser/pref_service.h"
 #include "chrome/browser/profile.h"
+#include "chrome/common/chrome_switches.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/sqlite_utils.h"
 #include "chrome/common/url_constants.h"
@@ -149,25 +151,31 @@ void HistoryURLProvider::DoAutocomplete(history::HistoryBackend* backend,
   typedef std::vector<history::URLRow> URLRowVector;
   URLRowVector url_matches;
   HistoryMatches history_matches;
-  for (Prefixes::const_iterator i(prefixes_.begin()); i != prefixes_.end();
-       ++i) {
-    if (params->cancel)
-      return;  // Canceled in the middle of a query, give up.
-    // We only need kMaxMatches results in the end, but before we get there we
-    // need to promote lower-quality matches that are prefixes of
-    // higher-quality matches, and remove lower-quality redirects.  So we ask
-    // for more results than we need, of every prefix type, in hopes this will
-    // give us far more than enough to work with.  CullRedirects() will then
-    // reduce the list to the best kMaxMatches results.
-    db->AutocompleteForPrefix(WideToUTF16(i->prefix + params->input.text()),
-                              kMaxMatches * 2, &url_matches);
-    for (URLRowVector::const_iterator j(url_matches.begin());
-         j != url_matches.end(); ++j) {
-      const Prefix* best_prefix = BestPrefix(j->url(), std::wstring());
-      DCHECK(best_prefix != NULL);
-      history_matches.push_back(HistoryMatch(*j, i->prefix.length(),
-          !i->num_components,
-          i->num_components >= best_prefix->num_components));
+
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableInMemoryURLIndex)) {
+    // TODO(rohitrao): Fetch results from the index.
+  } else {
+    for (Prefixes::const_iterator i(prefixes_.begin()); i != prefixes_.end();
+         ++i) {
+      if (params->cancel)
+        return;  // Canceled in the middle of a query, give up.
+      // We only need kMaxMatches results in the end, but before we get there we
+      // need to promote lower-quality matches that are prefixes of
+      // higher-quality matches, and remove lower-quality redirects.  So we ask
+      // for more results than we need, of every prefix type, in hopes this will
+      // give us far more than enough to work with.  CullRedirects() will then
+      // reduce the list to the best kMaxMatches results.
+      db->AutocompleteForPrefix(WideToUTF16(i->prefix + params->input.text()),
+                                kMaxMatches * 2, &url_matches);
+      for (URLRowVector::const_iterator j(url_matches.begin());
+           j != url_matches.end(); ++j) {
+        const Prefix* best_prefix = BestPrefix(j->url(), std::wstring());
+        DCHECK(best_prefix != NULL);
+        history_matches.push_back(HistoryMatch(*j, i->prefix.length(),
+            !i->num_components,
+            i->num_components >= best_prefix->num_components));
+      }
     }
   }
 
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_;