Remove usage of the NotificationService in TabsDetectLanguageFunction

Bug: 170921
Change-Id: If5a365004c7b9daac05132c6f2149e2abf49160e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1648708Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: Patrick Monette <pmonette@chromium.org>
Cr-Commit-Position: refs/heads/master@{#668601}

chrome/browser/extensions/BUILD.gn

@@ -839,7 +839,7 @@ jumbo_static_library("extensions") {
     "//components/sync",
     "//components/sync_preferences",
     "//components/sync_sessions",
-    "//components/translate/core/browser",
+    "//components/translate/content/browser",
     "//components/undo",
     "//components/unified_consent",
     "//components/update_client",

chrome/browser/extensions/api/tabs/tabs_api.cc

@@ -26,7 +26,6 @@
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "chrome/browser/browser_process.h"
-#include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/api/tabs/tabs_constants.h"
 #include "chrome/browser/extensions/api/tabs/tabs_util.h"
 #include "chrome/browser/extensions/api/tabs/windows_util.h"
@@ -68,8 +67,6 @@
 #include "components/zoom/zoom_controller.h"
 #include "content/public/browser/navigation_controller.h"
 #include "content/public/browser/navigation_entry.h"
-#include "content/public/browser/notification_details.h"
-#include "content/public/browser/notification_source.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
@@ -1785,7 +1782,7 @@ ExtensionFunction::ResponseAction TabsDetectLanguageFunction::Run() {
         Error(tabs_constants::kCannotDetermineLanguageOfUnloadedTab));
   }
 
-  AddRef();  // Balanced in GotLanguage().
+  AddRef();  // Balanced in RespondWithLanguage().
 
   ChromeTranslateClient* chrome_translate_client =
       ChromeTranslateClient::FromWebContents(contents);
@@ -1797,45 +1794,52 @@ ExtensionFunction::ResponseAction TabsDetectLanguageFunction::Run() {
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE,
         base::BindOnce(
-            &TabsDetectLanguageFunction::GotLanguage, this,
+            &TabsDetectLanguageFunction::RespondWithLanguage, this,
             chrome_translate_client->GetLanguageState().original_language()));
     return RespondLater();
   }
-  // The tab contents does not know its language yet.  Let's wait until it
+
+  // The tab contents does not know its language yet. Let's wait until it
   // receives it, or until the tab is closed/navigates to some other page.
-  registrar_.Add(this, chrome::NOTIFICATION_TAB_LANGUAGE_DETERMINED,
-                 content::Source<WebContents>(contents));
-  registrar_.Add(
-      this, chrome::NOTIFICATION_TAB_CLOSING,
-      content::Source<NavigationController>(&(contents->GetController())));
-  registrar_.Add(
-      this, content::NOTIFICATION_NAV_ENTRY_COMMITTED,
-      content::Source<NavigationController>(&(contents->GetController())));
+
+  // Observe the WebContents' lifetime and navigations.
+  Observe(contents);
+  // Wait until the language is determined.
+  chrome_translate_client->translate_driver().AddObserver(this);
+  is_observing_ = true;
+
   return RespondLater();
 }
 
-void TabsDetectLanguageFunction::Observe(
-    int type,
-    const content::NotificationSource& source,
-    const content::NotificationDetails& details) {
-  std::string language;
-  if (type == chrome::NOTIFICATION_TAB_LANGUAGE_DETERMINED) {
-    const translate::LanguageDetectionDetails* lang_det_details =
-        content::Details<const translate::LanguageDetectionDetails>(details)
-            .ptr();
-    language = lang_det_details->adopted_language;
-  }
+void TabsDetectLanguageFunction::NavigationEntryCommitted(
+    const content::LoadCommittedDetails& load_details) {
+  // Call RespondWithLanguage() with an empty string as we want to guarantee the
+  // callback is called for every API call the extension made.
+  RespondWithLanguage(std::string());
+}
 
-  registrar_.RemoveAll();
+void TabsDetectLanguageFunction::WebContentsDestroyed() {
+  // Call RespondWithLanguage() with an empty string as we want to guarantee the
+  // callback is called for every API call the extension made.
+  RespondWithLanguage(std::string());
+}
 
-  // Call GotLanguage in all cases as we want to guarantee the callback is
-  // called for every API call the extension made.
-  GotLanguage(language);
+void TabsDetectLanguageFunction::OnLanguageDetermined(
+    const translate::LanguageDetectionDetails& details) {
+  RespondWithLanguage(details.adopted_language);
 }
 
-void TabsDetectLanguageFunction::GotLanguage(const std::string& language) {
-  Respond(OneArgument(std::make_unique<base::Value>(language)));
+void TabsDetectLanguageFunction::RespondWithLanguage(
+    const std::string& language) {
+  // Stop observing.
+  if (is_observing_) {
+    ChromeTranslateClient::FromWebContents(web_contents())
+        ->translate_driver()
+        .RemoveObserver(this);
+    Observe(nullptr);
+  }
 
+  Respond(OneArgument(std::make_unique<base::Value>(language)));
   Release();  // Balanced in Run()
 }
 

chrome/browser/extensions/api/tabs/tabs_api.h

@@ -11,9 +11,9 @@
 #include "base/compiler_specific.h"
 #include "chrome/browser/extensions/chrome_extension_function_details.h"
 #include "chrome/common/extensions/api/tabs.h"
+#include "components/translate/content/browser/content_translate_driver.h"
 #include "components/zoom/zoom_controller.h"
-#include "content/public/browser/notification_observer.h"
-#include "content/public/browser/notification_registrar.h"
+#include "content/public/browser/web_contents_observer.h"
 #include "extensions/browser/api/execute_code_function.h"
 #include "extensions/browser/api/web_contents_capture_client.h"
 #include "extensions/browser/extension_function.h"
@@ -180,17 +180,30 @@ class TabsRemoveFunction : public UIThreadExtensionFunction {
   bool RemoveTab(int tab_id, std::string* error);
   DECLARE_EXTENSION_FUNCTION("tabs.remove", TABS_REMOVE)
 };
-class TabsDetectLanguageFunction : public UIThreadExtensionFunction,
-                                   public content::NotificationObserver {
+class TabsDetectLanguageFunction
+    : public UIThreadExtensionFunction,
+      public content::WebContentsObserver,
+      public translate::ContentTranslateDriver::Observer {
  private:
   ~TabsDetectLanguageFunction() override {}
   ResponseAction Run() override;
 
-  void Observe(int type,
-               const content::NotificationSource& source,
-               const content::NotificationDetails& details) override;
-  void GotLanguage(const std::string& language);
-  content::NotificationRegistrar registrar_;
+  // content::WebContentsObserver:
+  void NavigationEntryCommitted(
+      const content::LoadCommittedDetails& load_details) override;
+  void WebContentsDestroyed() override;
+
+  // translate::ContentTranslateDriver::Observer:
+  void OnLanguageDetermined(
+      const translate::LanguageDetectionDetails& details) override;
+
+  // Resolves the API call with the detected |language|.
+  void RespondWithLanguage(const std::string& language);
+
+  // Indicates if this instance is observing the tabs' WebContents and the
+  // ContentTranslateDriver, in which case the observers must be unregistered.
+  bool is_observing_ = false;
+
   DECLARE_EXTENSION_FUNCTION("tabs.detectLanguage", TABS_DETECTLANGUAGE)
 };