[omnibox] Combine AutocompleteController observer classes

This CL combines AutocompleteControllerDelegate and
OmniboxControllerEmitter::Observer classes into a single
AutocompleteController::Observer class.

This is because these two classes are essentially the same, both
observing the AutocompleteController.

In the future, we can also make OmniboxControllerEmitter itself an
instance of AutocompleteController::Observer, because it too, is
essentially an observer class that's a KeyedService.

The ultimate goal is to hook up the Android omnibox and NTP realbox
to the chrome://omnibox debug surfaces.

This refactor is to pave the way for that. See the bug for the full
engineering plan on how to get there.

Bug: 1058486
Change-Id: Ieb65cc2570a5af1ba417be6a87f4779bbe4710ce
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2088223Reviewed-by: Ted Choc <tedchoc@chromium.org>
Reviewed-by: Justin Donnelly <jdonnelly@chromium.org>
Commit-Queue: Tommy Li <tommycli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#751822}

chrome/browser/android/omnibox/autocomplete_controller_android.cc

@@ -36,7 +36,6 @@
 #include "components/bookmarks/browser/bookmark_model.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "components/omnibox/browser/autocomplete_classifier.h"
-#include "components/omnibox/browser/autocomplete_controller.h"
 #include "components/omnibox/browser/autocomplete_input.h"
 #include "components/omnibox/browser/autocomplete_match.h"
 #include "components/omnibox/browser/autocomplete_match_type.h"
@@ -105,17 +104,13 @@ void RecordClipboardMetrics(AutocompleteMatchType::Type match_type) {
  * The prefetch occurs as a side-effect of calling OnOmniboxFocused() on
  * the AutocompleteController object.
  */
-class ZeroSuggestPrefetcher : public AutocompleteControllerDelegate {
+class ZeroSuggestPrefetcher {
  public:
   explicit ZeroSuggestPrefetcher(Profile* profile);
 
  private:
-  ~ZeroSuggestPrefetcher() override = default;
   void SelfDestruct();
 
-  // AutocompleteControllerDelegate:
-  void OnResultChanged(bool default_match_changed) override;
-
   std::unique_ptr<AutocompleteController> controller_;
   base::OneShotTimer expire_timer_;
 };
@@ -123,7 +118,7 @@ class ZeroSuggestPrefetcher : public AutocompleteControllerDelegate {
 ZeroSuggestPrefetcher::ZeroSuggestPrefetcher(Profile* profile)
     : controller_(new AutocompleteController(
           std::make_unique<ChromeAutocompleteProviderClient>(profile),
-          this,
+          nullptr,  // We only want to warm up the cache, don't need the result.
           AutocompleteProvider::TYPE_ZERO_SUGGEST)) {
   AutocompleteInput input(base::string16(), metrics::OmniboxEventProto::NTP,
                           ChromeAutocompleteSchemeClassifier(profile));
@@ -140,12 +135,6 @@ void ZeroSuggestPrefetcher::SelfDestruct() {
   delete this;
 }
 
-void ZeroSuggestPrefetcher::OnResultChanged(bool default_match_changed) {
-  // Nothing to do here, the results have been cached.
-  // We don't want to trigger deletion here because this is being called by the
-  // AutocompleteController object.
-}
-
 }  // namespace
 
 AutocompleteControllerAndroid::AutocompleteControllerAndroid(Profile* profile)
@@ -400,7 +389,9 @@ void AutocompleteControllerAndroid::InitJNI(JNIEnv* env, jobject obj) {
 }
 
 void AutocompleteControllerAndroid::OnResultChanged(
+    AutocompleteController* controller,
     bool default_match_changed) {
+  DCHECK(controller == autocomplete_controller_.get());
   if (autocomplete_controller_ && !inside_synchronous_start_)
     NotifySuggestionsReceived(autocomplete_controller_->result());
 }

chrome/browser/android/omnibox/autocomplete_controller_android.h

@@ -13,7 +13,7 @@
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 #include "components/keyed_service/core/keyed_service.h"
-#include "components/omnibox/browser/autocomplete_controller_delegate.h"
+#include "components/omnibox/browser/autocomplete_controller.h"
 #include "components/omnibox/browser/autocomplete_input.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
@@ -26,7 +26,7 @@ class AutocompleteResult;
 class Profile;
 
 // The native part of the Java AutocompleteController class.
-class AutocompleteControllerAndroid : public AutocompleteControllerDelegate,
+class AutocompleteControllerAndroid : public AutocompleteController::Observer,
                                       public KeyedService {
  public:
   explicit AutocompleteControllerAndroid(Profile* profile);
@@ -112,8 +112,9 @@ class AutocompleteControllerAndroid : public AutocompleteControllerDelegate,
   ~AutocompleteControllerAndroid() override;
   void InitJNI(JNIEnv* env, jobject obj);
 
-  // AutocompleteControllerDelegate implementation.
-  void OnResultChanged(bool default_match_changed) override;
+  // AutocompleteController::Observer implementation.
+  void OnResultChanged(AutocompleteController* controller,
+                       bool default_match_changed) override;
 
   // Notifies the Java AutocompleteController that suggestions were received
   // based on the text the user typed in last.

chrome/browser/android/vr/autocomplete_controller.cc

@@ -11,7 +11,6 @@
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/vr/model/omnibox_suggestions.h"
 #include "components/omnibox/browser/autocomplete_classifier.h"
-#include "components/omnibox/browser/autocomplete_controller.h"
 #include "components/omnibox/browser/autocomplete_input.h"
 #include "components/search_engines/util.h"
 
@@ -71,7 +70,11 @@ std::tuple<GURL, bool> AutocompleteController::GetUrlFromVoiceInput(
           false};
 }
 
-void AutocompleteController::OnResultChanged(bool default_match_changed) {
+void AutocompleteController::OnResultChanged(
+    ::AutocompleteController* controller,
+    bool default_match_changed) {
+  DCHECK(controller == autocomplete_controller_.get());
+
   std::vector<OmniboxSuggestion> suggestions;
   for (const auto& match : autocomplete_controller_->result()) {
     const gfx::VectorIcon* icon = &match.GetVectorIcon(false);

chrome/browser/android/vr/autocomplete_controller.h

@@ -12,7 +12,7 @@
 #include "base/macros.h"
 #include "base/values.h"
 #include "chrome/browser/vr/model/omnibox_suggestions.h"
-#include "components/omnibox/browser/autocomplete_controller_delegate.h"
+#include "components/omnibox/browser/autocomplete_controller.h"
 #include "url/gurl.h"
 
 class AutocompleteController;
@@ -21,7 +21,7 @@ class Profile;
 
 namespace vr {
 
-class AutocompleteController : public AutocompleteControllerDelegate {
+class AutocompleteController : public ::AutocompleteController::Observer {
  public:
   using SuggestionCallback =
       base::RepeatingCallback<void(std::vector<OmniboxSuggestion>)>;
@@ -41,7 +41,9 @@ class AutocompleteController : public AutocompleteControllerDelegate {
   std::tuple<GURL, bool> GetUrlFromVoiceInput(const base::string16& input);
 
  private:
-  void OnResultChanged(bool default_match_changed) override;
+  // ::AutocompleteController::Observer:
+  void OnResultChanged(::AutocompleteController* controller,
+                       bool default_match_changed) override;
 
   Profile* profile_;
   ChromeAutocompleteProviderClient* client_;

chrome/browser/ui/app_list/search/omnibox_provider.cc

@@ -14,7 +14,6 @@
 #include "chrome/browser/ui/app_list/app_list_controller_delegate.h"
 #include "chrome/browser/ui/app_list/search/omnibox_result.h"
 #include "components/omnibox/browser/autocomplete_classifier.h"
-#include "components/omnibox/browser/autocomplete_controller.h"
 #include "components/omnibox/browser/autocomplete_input.h"
 #include "third_party/metrics_proto/omnibox_event.pb.h"
 #include "url/gurl.h"
@@ -76,7 +75,10 @@ void OmniboxProvider::PopulateFromACResult(const AutocompleteResult& result) {
   SwapResults(&new_results);
 }
 
-void OmniboxProvider::OnResultChanged(bool default_match_changed) {
+void OmniboxProvider::OnResultChanged(AutocompleteController* controller,
+                                      bool default_match_changed) {
+  DCHECK(controller == controller_.get());
+
   // Record the query latency.
   RecordQueryLatencyHistogram();
 

chrome/browser/ui/app_list/search/omnibox_provider.h

@@ -9,7 +9,7 @@
 
 #include "base/macros.h"
 #include "chrome/browser/ui/app_list/search/search_provider.h"
-#include "components/omnibox/browser/autocomplete_controller_delegate.h"
+#include "components/omnibox/browser/autocomplete_controller.h"
 
 class AppListControllerDelegate;
 class AutocompleteController;
@@ -20,7 +20,7 @@ namespace app_list {
 
 // OmniboxProvider wraps AutocompleteController to provide omnibox results.
 class OmniboxProvider : public SearchProvider,
-                        public AutocompleteControllerDelegate {
+                        public AutocompleteController::Observer {
  public:
   explicit OmniboxProvider(Profile* profile,
                            AppListControllerDelegate* list_controller);
@@ -33,8 +33,9 @@ class OmniboxProvider : public SearchProvider,
   // Populates result list from AutocompleteResult.
   void PopulateFromACResult(const AutocompleteResult& result);
 
-  // AutocompleteControllerDelegate overrides:
-  void OnResultChanged(bool default_match_changed) override;
+  // AutocompleteController::Observer overrides:
+  void OnResultChanged(AutocompleteController* controller,
+                       bool default_match_changed) override;
 
   void RecordQueryLatencyHistogram();
 

chrome/browser/ui/search/search_tab_helper.cc

@@ -449,7 +449,10 @@ void SearchTabHelper::FileSelectionCanceled(void* params) {
       ->LogEvent(NTP_BACKGROUND_UPLOAD_CANCEL, base::TimeDelta::FromSeconds(0));
 }
 
-void SearchTabHelper::OnResultChanged(bool default_result_changed) {
+void SearchTabHelper::OnResultChanged(AutocompleteController* controller,
+                                      bool default_result_changed) {
+  DCHECK(controller == autocomplete_controller_.get());
+
   if (!autocomplete_controller_) {
     NOTREACHED();
     return;

chrome/browser/ui/search/search_tab_helper.h

@@ -23,7 +23,7 @@
 #include "chrome/common/search/instant_types.h"
 #include "chrome/common/search/ntp_logging_events.h"
 #include "components/ntp_tiles/ntp_tile_impression.h"
-#include "components/omnibox/browser/autocomplete_controller_delegate.h"
+#include "components/omnibox/browser/autocomplete_controller.h"
 #include "components/omnibox/common/omnibox_focus_state.h"
 #include "content/public/browser/reload_type.h"
 #include "content/public/browser/web_contents_observer.h"
@@ -54,7 +54,7 @@ class SearchTabHelper : public content::WebContentsObserver,
                         public InstantServiceObserver,
                         public SearchIPCRouter::Delegate,
                         public ui::SelectFileDialog::Listener,
-                        public AutocompleteControllerDelegate,
+                        public AutocompleteController::Observer,
                         public OmniboxTabHelper::Observer {
  public:
   ~SearchTabHelper() override;
@@ -164,8 +164,9 @@ class SearchTabHelper : public content::WebContentsObserver,
                     void* params) override;
   void FileSelectionCanceled(void* params) override;
 
-  // Overridden from AutocompleteControllerDelegate:
-  void OnResultChanged(bool default_match_changed) override;
+  // Overridden from AutocompleteController::Observer:
+  void OnResultChanged(AutocompleteController* controller,
+                       bool default_match_changed) override;
 
   // Overridden from OmniboxTabHelper::Observer:
   void OnOmniboxInputStateChanged() override;

chrome/browser/ui/webui/omnibox/omnibox_page_handler.cc

@@ -29,7 +29,6 @@
 #include "components/history/core/browser/history_service.h"
 #include "components/history/core/browser/url_database.h"
 #include "components/omnibox/browser/autocomplete_classifier.h"
-#include "components/omnibox/browser/autocomplete_controller.h"
 #include "components/omnibox/browser/autocomplete_match.h"
 #include "components/omnibox/browser/autocomplete_provider.h"
 #include "components/omnibox/browser/omnibox_controller_emitter.h"
@@ -205,23 +204,18 @@ OmniboxPageHandler::OmniboxPageHandler(
   ResetController();
 }
 
-OmniboxPageHandler::~OmniboxPageHandler() {}
+OmniboxPageHandler::~OmniboxPageHandler() = default;
 
-void OmniboxPageHandler::OnResultChanged(bool default_match_changed) {
-  OnOmniboxResultChanged(default_match_changed, controller_.get());
-}
-
-void OmniboxPageHandler::OnOmniboxQuery(AutocompleteController* controller,
-                                        const AutocompleteInput& input) {
+void OmniboxPageHandler::OnStart(AutocompleteController* controller,
+                                 const AutocompleteInput& input) {
   time_omnibox_started_ = base::Time::Now();
   input_ = input;
   page_->HandleNewAutocompleteQuery(controller == controller_.get(),
                                     base::UTF16ToUTF8(input.text()));
 }
 
-void OmniboxPageHandler::OnOmniboxResultChanged(
-    bool default_match_changed,
-    AutocompleteController* controller) {
+void OmniboxPageHandler::OnResultChanged(AutocompleteController* controller,
+                                         bool default_match_changed) {
   mojom::OmniboxResponsePtr response(mojom::OmniboxResponse::New());
   response->cursor_position = input_.cursor_position();
   response->time_since_omnibox_started_ms =
@@ -355,8 +349,7 @@ void OmniboxPageHandler::StartOmniboxQuery(const std::string& input_string,
     input.set_keyword_mode_entry_method(metrics::OmniboxEventProto::TAB);
   input.set_from_omnibox_focus(zero_suggest);
 
-  OnOmniboxQuery(controller_.get(), input);
-  controller_->Start(input_);
+  controller_->Start(input);
 }
 
 void OmniboxPageHandler::ResetController() {

chrome/browser/ui/webui/omnibox/omnibox_page_handler.h

@@ -14,7 +14,7 @@
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
 #include "chrome/browser/ui/webui/omnibox/omnibox.mojom.h"
-#include "components/omnibox/browser/autocomplete_controller_delegate.h"
+#include "components/omnibox/browser/autocomplete_controller.h"
 #include "components/omnibox/browser/autocomplete_input.h"
 #include "components/omnibox/browser/autocomplete_match.h"
 #include "components/omnibox/browser/omnibox_controller_emitter.h"
@@ -30,23 +30,19 @@ class Profile;
 // private AutocompleteController. It also listens for updates from the
 // AutocompleteController to OnResultChanged() and passes those results to
 // the OmniboxPage.
-class OmniboxPageHandler : public AutocompleteControllerDelegate,
-                           public mojom::OmniboxPageHandler,
-                           public OmniboxControllerEmitter::Observer {
+class OmniboxPageHandler : public AutocompleteController::Observer,
+                           public mojom::OmniboxPageHandler {
  public:
   // OmniboxPageHandler is deleted when the supplied pipe is destroyed.
   OmniboxPageHandler(Profile* profile,
                      mojo::PendingReceiver<mojom::OmniboxPageHandler> receiver);
   ~OmniboxPageHandler() override;
 
-  // AutocompleteControllerDelegate overrides:
-  void OnResultChanged(bool default_match_changed) override;
-
-  // OmniboxControllerEmitter::Observer overrides:
-  void OnOmniboxQuery(AutocompleteController* controller,
-                      const AutocompleteInput& input) override;
-  void OnOmniboxResultChanged(bool default_match_changed,
-                              AutocompleteController* controller) override;
+  // AutocompleteController::Observer overrides:
+  void OnStart(AutocompleteController* controller,
+               const AutocompleteInput& input) override;
+  void OnResultChanged(AutocompleteController* controller,
+                       bool default_match_changed) override;
 
   // mojom::OmniboxPageHandler overrides:
   void SetClientPage(mojo::PendingRemote<mojom::OmniboxPage> page) override;
@@ -93,7 +89,7 @@ class OmniboxPageHandler : public AutocompleteControllerDelegate,
 
   mojo::Receiver<mojom::OmniboxPageHandler> receiver_;
 
-  ScopedObserver<OmniboxControllerEmitter, OmniboxControllerEmitter::Observer>
+  ScopedObserver<OmniboxControllerEmitter, AutocompleteController::Observer>
       observer_;
 
   base::WeakPtrFactory<OmniboxPageHandler> weak_factory_{this};

chrome/test/base/ui_test_utils.cc

@@ -206,7 +206,7 @@ class BrowserChangeObserver : public BrowserListObserver {
   DISALLOW_COPY_AND_ASSIGN(BrowserChangeObserver);
 };
 
-class AutocompleteChangeObserver : public OmniboxControllerEmitter::Observer {
+class AutocompleteChangeObserver : public AutocompleteController::Observer {
  public:
   explicit AutocompleteChangeObserver(Profile* profile) {
     scoped_observer_.Add(
@@ -217,18 +217,16 @@ class AutocompleteChangeObserver : public OmniboxControllerEmitter::Observer {
 
   void Wait() { run_loop_.Run(); }
 
-  // OmniboxControllerEmitter::Observer:
-  void OnOmniboxQuery(AutocompleteController* controller,
-                      const AutocompleteInput& input) override {}
-  void OnOmniboxResultChanged(bool default_match_changed,
-                              AutocompleteController* controller) override {
+  // AutocompleteController::Observer:
+  void OnResultChanged(AutocompleteController* controller,
+                       bool default_match_changed) override {
     if (run_loop_.running())
       run_loop_.Quit();
   }
 
  private:
   base::RunLoop run_loop_;
-  ScopedObserver<OmniboxControllerEmitter, OmniboxControllerEmitter::Observer>
+  ScopedObserver<OmniboxControllerEmitter, AutocompleteController::Observer>
       scoped_observer_{this};
 
   DISALLOW_COPY_AND_ASSIGN(AutocompleteChangeObserver);

components/omnibox/browser/BUILD.gn

@@ -82,7 +82,6 @@ jumbo_static_library("browser") {
     "autocomplete_classifier.h",
     "autocomplete_controller.cc",
     "autocomplete_controller.h",
-    "autocomplete_controller_delegate.h",
     "autocomplete_input.cc",
     "autocomplete_input.h",
     "autocomplete_match.cc",

components/omnibox/browser/autocomplete_controller.cc

@@ -30,7 +30,6 @@
 #include "base/trace_event/memory_usage_estimator.h"
 #include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
-#include "components/omnibox/browser/autocomplete_controller_delegate.h"
 #include "components/omnibox/browser/bookmark_provider.h"
 #include "components/omnibox/browser/builtin_provider.h"
 #include "components/omnibox/browser/clipboard_provider.h"
@@ -208,10 +207,9 @@ bool AutocompleteMatchHasCustomDescription(const AutocompleteMatch& match) {
 
 AutocompleteController::AutocompleteController(
     std::unique_ptr<AutocompleteProviderClient> provider_client,
-    AutocompleteControllerDelegate* delegate,
+    Observer* observer,
     int provider_types)
-    : delegate_(delegate),
-      provider_client_(std::move(provider_client)),
+    : provider_client_(std::move(provider_client)),
       document_provider_(nullptr),
       history_url_provider_(nullptr),
       keyword_provider_(nullptr),
@@ -224,6 +222,11 @@ AutocompleteController::AutocompleteController(
       first_query_(true),
       search_service_worker_signal_sent_(false),
       template_url_service_(provider_client_->GetTemplateURLService()) {
+  // TODO(tommycli): We should make a separate AddObserver method on this class
+  // and take |observer| out of the constructor. Tests pass nullptr anyways.
+  if (observer)
+    observers_.AddObserver(observer);
+
   provider_types &= ~OmniboxFieldTrial::GetDisabledProviderTypes();
   if (provider_types & AutocompleteProvider::TYPE_BOOKMARK)
     providers_.push_back(new BookmarkProvider(provider_client_.get()));
@@ -327,6 +330,14 @@ AutocompleteController::~AutocompleteController() {
 void AutocompleteController::Start(const AutocompleteInput& input) {
   TRACE_EVENT1("omnibox", "AutocompleteController::Start",
                "text", base::UTF16ToUTF8(input.text()));
+
+  // When input.want_asynchronous_matches() is false, the AutocompleteController
+  // is being used for text classification, which should not notify observers.
+  if (input.want_asynchronous_matches()) {
+    for (Observer& obs : observers_)
+      obs.OnStart(this, input);
+  }
+
   const base::string16 old_input_text(input_.text());
   const bool old_allow_exact_keyword_match = input_.allow_exact_keyword_match();
   const bool old_want_asynchronous_matches = input_.want_asynchronous_matches();
@@ -855,8 +866,8 @@ void AutocompleteController::UpdateAssistedQueryStats(
 }
 
 void AutocompleteController::NotifyChanged(bool notify_default_match) {
-  if (delegate_)
-    delegate_->OnResultChanged(notify_default_match);
+  for (Observer& obs : observers_)
+    obs.OnResultChanged(this, notify_default_match);
   if (done_)
     provider_client_->OnAutocompleteControllerResultReady(this);
 }

components/omnibox/browser/autocomplete_controller.h

@@ -12,6 +12,8 @@
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
+#include "base/observer_list.h"
+#include "base/observer_list_types.h"
 #include "base/strings/string16.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
@@ -23,7 +25,6 @@
 #include "components/omnibox/browser/autocomplete_provider_listener.h"
 #include "components/omnibox/browser/autocomplete_result.h"
 
-class AutocompleteControllerDelegate;
 class DocumentProvider;
 class HistoryURLProvider;
 class KeywordProvider;
@@ -57,15 +58,32 @@ class AutocompleteController : public AutocompleteProviderListener,
  public:
   typedef std::vector<scoped_refptr<AutocompleteProvider> > Providers;
 
+  class Observer : public base::CheckedObserver {
+   public:
+    // Invoked when the |controller| Start() is called with an |input| that
+    // wants asynchronous matches. This is meant to exclude text classification
+    // requests. The |controller| parameter is only useful for observers that
+    // are observing multiple AutocompleteController instances.
+    virtual void OnStart(AutocompleteController* controller,
+                         const AutocompleteInput& input) {}
+
+    // Invoked when the result set of |controller| changes. If
+    // |default_match_changed| is true, the default match of the result set has
+    // changed. The |controller| parameter is only useful for observers that
+    // are observing multiple AutocompleteController instances.
+    virtual void OnResultChanged(AutocompleteController* controller,
+                                 bool default_match_changed) {}
+  };
+
   // |provider_types| is a bitmap containing AutocompleteProvider::Type values
   // that will (potentially, depending on platform, flags, etc.) be
   // instantiated. |provider_client| is passed to all those providers, and
-  // is used to get access to the template URL service. |delegate| is a
+  // is used to get access to the template URL service. |observer| is a
   // proxy for UI elements which need to be notified when the results get
   // updated.
   AutocompleteController(
       std::unique_ptr<AutocompleteProviderClient> provider_client,
-      AutocompleteControllerDelegate* delegate,
+      Observer* observer,
       int provider_types);
   ~AutocompleteController() override;
 
@@ -76,9 +94,9 @@ class AutocompleteController : public AutocompleteProviderListener,
   // See AutocompleteInput::AutocompleteInput(...) for more details regarding
   // |input| params.
   //
-  // The controller calls AutocompleteControllerDelegate::OnResultChanged() from
-  // inside this call at least once. If matches are available later on that
-  // result in changing the result set the delegate is notified again. When the
+  // The controller calls AutocompleteController::Observer::OnResultChanged()
+  // from inside this call at least once. If matches are available later on that
+  // result in changing the result set the observers is notified again. When the
   // controller is done the notification AUTOCOMPLETE_CONTROLLER_RESULT_READY is
   // sent.
   void Start(const AutocompleteInput& input);
@@ -214,7 +232,7 @@ class AutocompleteController : public AutocompleteProviderListener,
   // stats.
   void UpdateAssistedQueryStats(AutocompleteResult* result);
 
-  // Calls AutocompleteControllerDelegate::OnResultChanged() and if done sends
+  // Calls AutocompleteController::Observer::OnResultChanged() and if done sends
   // AUTOCOMPLETE_CONTROLLER_RESULT_READY.
   void NotifyChanged(bool notify_default_match);
 
@@ -242,7 +260,7 @@ class AutocompleteController : public AutocompleteProviderListener,
       const base::trace_event::MemoryDumpArgs& args,
       base::trace_event::ProcessMemoryDump* process_memory_dump) override;
 
-  AutocompleteControllerDelegate* delegate_;
+  base::ObserverList<Observer> observers_;
 
   // The client passed to the providers.
   std::unique_ptr<AutocompleteProviderClient> provider_client_;

components/omnibox/browser/autocomplete_controller_delegate.h

-// 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.
-
-#ifndef COMPONENTS_OMNIBOX_BROWSER_AUTOCOMPLETE_CONTROLLER_DELEGATE_H_
-#define COMPONENTS_OMNIBOX_BROWSER_AUTOCOMPLETE_CONTROLLER_DELEGATE_H_
-
-class AutocompleteControllerDelegate {
- public:
-  // Invoked when the result set of the AutocompleteController changes. If
-  // |default_match_changed| is true, the default match of the result set has
-  // changed.
-  virtual void OnResultChanged(bool default_match_changed) = 0;
-
- protected:
-  virtual ~AutocompleteControllerDelegate() {}
-};
-
-#endif  // COMPONENTS_OMNIBOX_BROWSER_AUTOCOMPLETE_CONTROLLER_DELEGATE_H_

components/omnibox/browser/omnibox_controller.cc

@@ -43,7 +43,10 @@ void OmniboxController::StartAutocomplete(
   autocomplete_controller_->Start(input);
 }
 
-void OmniboxController::OnResultChanged(bool default_match_changed) {
+void OmniboxController::OnResultChanged(AutocompleteController* controller,
+                                        bool default_match_changed) {
+  DCHECK(controller == autocomplete_controller_.get());
+
   if (client_->GetOmniboxControllerEmitter())
     client_->GetOmniboxControllerEmitter()->NotifyOmniboxResultChanged(
         default_match_changed, autocomplete_controller_.get());

components/omnibox/browser/omnibox_controller.h

@@ -11,7 +11,6 @@
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "components/omnibox/browser/autocomplete_controller.h"
-#include "components/omnibox/browser/autocomplete_controller_delegate.h"
 #include "components/omnibox/browser/autocomplete_match.h"
 
 struct AutocompleteMatch;
@@ -29,7 +28,7 @@ class OmniboxPopupModel;
 //     this the point of contact between InstantController and OmniboxEditModel.
 //     As the refactor progresses, keep the class comment up to date to
 //     precisely explain what this class is doing.
-class OmniboxController : public AutocompleteControllerDelegate {
+class OmniboxController : public AutocompleteController::Observer {
  public:
   OmniboxController(OmniboxEditModel* omnibox_edit_model,
                     OmniboxClient* client);
@@ -38,8 +37,9 @@ class OmniboxController : public AutocompleteControllerDelegate {
   // The |current_url| field of input is only set for mobile ports.
   void StartAutocomplete(const AutocompleteInput& input) const;
 
-  // AutocompleteControllerDelegate:
-  void OnResultChanged(bool default_match_changed) override;
+  // AutocompleteController::Observer:
+  void OnResultChanged(AutocompleteController* controller,
+                       bool default_match_changed) override;
 
   AutocompleteController* autocomplete_controller() {
     return autocomplete_controller_.get();

components/omnibox/browser/omnibox_controller_emitter.cc

@@ -59,24 +59,26 @@ OmniboxControllerEmitter* OmniboxControllerEmitter::GetForBrowserContext(
 }
 #endif  // !defined(OS_IOS)
 
-void OmniboxControllerEmitter::AddObserver(Observer* observer) {
+void OmniboxControllerEmitter::AddObserver(
+    AutocompleteController::Observer* observer) {
   observers_.AddObserver(observer);
 }
 
-void OmniboxControllerEmitter::RemoveObserver(Observer* observer) {
+void OmniboxControllerEmitter::RemoveObserver(
+    AutocompleteController::Observer* observer) {
   observers_.RemoveObserver(observer);
 }
 
 void OmniboxControllerEmitter::NotifyOmniboxQuery(
     AutocompleteController* controller,
     const AutocompleteInput& input) {
-  for (Observer& observer : observers_)
-    observer.OnOmniboxQuery(controller, input);
+  for (auto& observer : observers_)
+    observer.OnStart(controller, input);
 }
 
 void OmniboxControllerEmitter::NotifyOmniboxResultChanged(
     bool default_match_changed,
     AutocompleteController* controller) {
-  for (Observer& observer : observers_)
-    observer.OnOmniboxResultChanged(default_match_changed, controller);
+  for (auto& observer : observers_)
+    observer.OnResultChanged(controller, default_match_changed);
 }

components/omnibox/browser/omnibox_controller_emitter.h

@@ -8,7 +8,6 @@
 #include "build/build_config.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/omnibox/browser/autocomplete_controller.h"
-#include "components/omnibox/browser/autocomplete_controller_delegate.h"
 
 #if !defined(OS_IOS)
 #include "content/public/browser/browser_context.h"
@@ -18,16 +17,6 @@
 // and notifies observers (chrome://omnibox debug page).
 class OmniboxControllerEmitter : public KeyedService {
  public:
-  class Observer : public base::CheckedObserver {
-   public:
-    // Invoked when new autocomplete queries are made from the omnibox
-    // controller or when those queries' results change.
-    virtual void OnOmniboxQuery(AutocompleteController* controller,
-                                const AutocompleteInput& input) = 0;
-    virtual void OnOmniboxResultChanged(bool default_match_changed,
-                                        AutocompleteController* controller) = 0;
-  };
-
 #if !defined(OS_IOS)
   static OmniboxControllerEmitter* GetForBrowserContext(
       content::BrowserContext* browser_context);
@@ -37,18 +26,21 @@ class OmniboxControllerEmitter : public KeyedService {
   ~OmniboxControllerEmitter() override;
 
   // Add/remove observer.
-  void AddObserver(Observer* observer);
-  void RemoveObserver(Observer* observer);
+  void AddObserver(AutocompleteController::Observer* observer);
+  void RemoveObserver(AutocompleteController::Observer* observer);
 
   // Notifies registered observers when new autocomplete queries are made from
   // the omnibox controller or when those queries' results change.
+  //
+  // TODO(tommycli): These two methods themselves should be overrides of
+  // AutocompleteController::Observer.
   void NotifyOmniboxQuery(AutocompleteController* controller,
                           const AutocompleteInput& input);
   void NotifyOmniboxResultChanged(bool default_match_changed,
                                   AutocompleteController* controller);
 
  private:
-  base::ObserverList<Observer> observers_;
+  base::ObserverList<AutocompleteController::Observer> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(OmniboxControllerEmitter);
 };

components/omnibox/browser/omnibox_edit_model.h

@@ -14,7 +14,6 @@
 #include "base/strings/string16.h"
 #include "base/time/time.h"
 #include "components/omnibox/browser/autocomplete_controller.h"
-#include "components/omnibox/browser/autocomplete_controller_delegate.h"
 #include "components/omnibox/browser/autocomplete_input.h"
 #include "components/omnibox/browser/autocomplete_match.h"
 #include "components/omnibox/browser/omnibox_controller.h"