Implements the auto-translate on click: if you have translated

a page and are navigating to a new page in the same language by
clicking a link, the new page is automatically translated.
In order to do that I moved the language state from the navigation
entry to some dedicated class that each TabContents owns.
Also added some basic unit-testing for good measure.

BUG=35477
TEST=See bug steps. Run unit-tests.
 
Review URL: http://codereview.chromium.org/596092

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@38961 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 152 insertions, 16 deletions

diff --git a/chrome/browser/tab_contents/language_state.cc b/chrome/browser/tab_contents/language_state.cc
new file mode 100644
index 0000000..8522ed3
--- /dev/null
+++ b/chrome/browser/tab_contents/language_state.cc
@@ -0,0 +1,51 @@
+// 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/tab_contents/language_state.h"
+
+#include "chrome/browser/tab_contents/navigation_controller.h"
+#include "chrome/browser/tab_contents/navigation_entry.h"
+
+LanguageState::LanguageState(NavigationController* nav_controller)
+    : navigation_controller_(nav_controller),
+      translation_pending_(false) {
+}
+
+LanguageState::~LanguageState() {
+}
+
+void LanguageState::DidNavigate() {
+  prev_original_lang_ = original_lang_;
+  prev_current_lang_ = current_lang_;
+
+  original_lang_.clear();
+  current_lang_.clear();
+
+  translation_pending_ = false;
+}
+
+void LanguageState::LanguageDetermined(const std::string& page_language) {
+  original_lang_ = page_language;
+  current_lang_ = page_language;
+}
+
+std::string LanguageState::AutoTranslateTo() const {
+  // Only auto-translate if:
+  // - no translation is pending
+  // - this page is in the same language as the previous page
+  // - the previous page had been translated
+  // - this page is not already translated
+  // - the new page was navigated through a link.
+  if (!translation_pending_ &&
+      prev_original_lang_ == original_lang_ &&
+      prev_original_lang_ != prev_current_lang_ &&
+      original_lang_ == current_lang_ &&
+      navigation_controller_->GetActiveEntry() &&
+      navigation_controller_->GetActiveEntry()->transition_type() ==
+          PageTransition::LINK) {
+    return prev_current_lang_;
+  }
+
+  return std::string();
+}
diff --git a/chrome/browser/tab_contents/language_state.h b/chrome/browser/tab_contents/language_state.h
new file mode 100644
index 0000000..d5c7df6
--- /dev/null
+++ b/chrome/browser/tab_contents/language_state.h
@@ -0,0 +1,84 @@
+// 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 CHROME_BROWSER_TAB_CONTENTS_LANGUAGE_STATE_H_
+#define CHROME_BROWSER_TAB_CONTENTS_LANGUAGE_STATE_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+
+class NavigationController;
+
+// This class holds the language state of the current page.
+// There is one LanguageState instance per TabContents.
+// It is used to determine when navigating to a new page whether it should
+// automatically be translated.
+// This auto-translate behavior is the expected behavior when:
+// - user is on page in language A that they had translated to language B.
+// - user clicks a link in that page that takes them to a page also in language
+//   A.
+
+class LanguageState {
+ public:
+  explicit LanguageState(NavigationController* nav_controller);
+  ~LanguageState();
+
+  // Should be called when the page did a new navigation (whether it is a main
+  // frame or sub-frame navigation).
+  void DidNavigate();
+
+  // Should be called when the language of the page has been determined.
+  void LanguageDetermined(const std::string& page_language);
+
+  // Returns the language the current page should be translated to, based on the
+  // previous page languages and the transition.  This should be called after
+  // the language page has been determined.
+  // Returns an empty string if the page should not be auto-translated.
+  std::string AutoTranslateTo() const;
+
+  // Returns true if the current page in the associated tab has been translated.
+  bool IsPageTranslated() const { return original_lang_ != current_lang_; }
+
+  const std::string& original_language() const { return original_lang_; }
+
+  void set_current_language(const std::string& language) {
+    current_lang_ = language;
+  }
+  const std::string& current_language() const { return current_lang_; }
+
+  // Whether the page is currently in the process of being translated.
+  bool translation_pending() const { return translation_pending_; }
+  void set_translation_pending(bool value) { translation_pending_ = value; }
+
+ private:
+  // The languages this page is in. Note that current_lang_ is different from
+  // original_lang_ when the page has been translated.
+  // Note that these might be empty if the page language has not been determined
+  // yet.
+  std::string original_lang_;
+  std::string current_lang_;
+
+  // Same as above but for the previous page.
+  std::string prev_original_lang_;
+  std::string prev_current_lang_;
+
+  // The navigation controller of the tab we are associated with.
+  NavigationController* navigation_controller_;
+
+  // Whether a translation is currently pending (TabContents waiting for the
+  // PAGE_TRANSLATED notification).  This is needed to avoid sending duplicate
+  // translate requests to a page.  TranslateManager initiates translations
+  // when it received the LANGUAGE_DETERMINED notification.  This is sent by
+  // the renderer with the page contents, every time the load stops for the
+  // main frame, so we may get several.
+  // TODO(jcampan): make the renderer send the language just once per navigation
+  //                then we can get rid of that state.
+  bool translation_pending_;
+
+  DISALLOW_COPY_AND_ASSIGN(LanguageState);
+};
+
+#endif  // CHROME_BROWSER_TAB_CONTENTS_LANGUAGE_STATE_H_
+
diff --git a/chrome/browser/tab_contents/navigation_entry.h b/chrome/browser/tab_contents/navigation_entry.h
index df6ad06..e679c10 100644
--- a/chrome/browser/tab_contents/navigation_entry.h
+++ b/chrome/browser/tab_contents/navigation_entry.h
@@ -389,15 +389,6 @@ class NavigationEntry {
     return restore_type_;
   }
 
-  // The ISO 639-1 language code (ex: en, fr, zh...) for the page.
-  // Can be empty if the language was not detected yet or is unknown.
-  void set_language(const std::string& language) {
-    language_ = language;
-  }
-  std::string language() const {
-    return language_;
-  }
-
  private:
   // WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
   // Session/Tab restore save portions of this class so that it can be recreated
@@ -422,7 +413,6 @@ class NavigationEntry {
   GURL user_typed_url_;
   bool has_post_data_;
   RestoreType restore_type_;
-  std::string language_;  // ISO 639-1 language code.
 
   // This is a cached version of the result of GetTitleForDisplay. It prevents
   // us from having to do URL formatting on the URL evey time the title is
diff --git a/chrome/browser/tab_contents/tab_contents.cc b/chrome/browser/tab_contents/tab_contents.cc
index 2f0dcd9..ed15084 100644
--- a/chrome/browser/tab_contents/tab_contents.cc
+++ b/chrome/browser/tab_contents/tab_contents.cc
@@ -269,7 +269,8 @@ TabContents::TabContents(Profile* profile,
       is_showing_before_unload_dialog_(false),
       renderer_preferences_(),
       opener_dom_ui_type_(DOMUIFactory::kNoDOMUI),
-      app_extension_(NULL) {
+      app_extension_(NULL),
+      language_state_(&controller_) {
   ClearBlockedContentSettings();
   renderer_preferences_util::UpdateFromSystemSettings(
       &renderer_preferences_, profile);
@@ -811,6 +812,7 @@ void TabContents::TranslatePage(const std::string& source_lang,
     NOTREACHED();
     return;
   }
+  language_state_.set_translation_pending(true);
   render_view_host()->TranslatePage(entry->page_id(), source_lang, target_lang);
 }
 
@@ -1503,6 +1505,9 @@ void TabContents::DidNavigateAnyFramePostCommit(
   // cleaned up and covered by tests.
   if (params.password_form.origin.is_valid())
     GetPasswordManager()->ProvisionallySavePassword(params.password_form);
+
+  // Let the LanguageState clear its state.
+  language_state_.DidNavigate();
 }
 
 void TabContents::CloseConstrainedWindows() {
@@ -1860,11 +1865,7 @@ void TabContents::OnPageContents(const GURL& url,
     }
   }
 
-  NavigationEntry* entry = controller_.GetActiveEntry();
-  if (GetRenderProcessHost()->id() == renderer_process_id &&
-      entry && entry->page_id() == page_id) {
-    entry->set_language(language);
-  }
+  language_state_.LanguageDetermined(language);
 
   std::string lang = language;
   NotificationService::current()->Notify(
@@ -1876,6 +1877,8 @@ void TabContents::OnPageContents(const GURL& url,
 void TabContents::OnPageTranslated(int32 page_id,
                                    const std::string& original_lang,
                                    const std::string& translated_lang) {
+  language_state_.set_current_language(translated_lang);
+  language_state_.set_translation_pending(false);
   std::pair<std::string, std::string> lang_pair =
       std::make_pair(original_lang, translated_lang);
   NotificationService::current()->Notify(
diff --git a/chrome/browser/tab_contents/tab_contents.h b/chrome/browser/tab_contents/tab_contents.h
index 2c7e5be..4d11745 100644
--- a/chrome/browser/tab_contents/tab_contents.h
+++ b/chrome/browser/tab_contents/tab_contents.h
@@ -30,6 +30,7 @@
 #include "chrome/browser/renderer_host/render_view_host_delegate.h"
 #include "chrome/browser/tab_contents/constrained_window.h"
 #include "chrome/browser/tab_contents/infobar_delegate.h"
+#include "chrome/browser/tab_contents/language_state.h"
 #include "chrome/browser/tab_contents/navigation_controller.h"
 #include "chrome/browser/tab_contents/navigation_entry.h"
 #include "chrome/browser/tab_contents/page_navigator.h"
@@ -639,6 +640,10 @@ class TabContents : public PageNavigator,
     return request_context_;
   }
 
+  LanguageState& language_state() {
+    return language_state_;
+  }
+
   // Creates a duplicate of this TabContents. The returned TabContents is
   // configured such that the renderer has not been loaded (it'll load the first
   // time it is selected).
@@ -1180,6 +1185,9 @@ class TabContents : public PageNavigator,
   // created for.
   Extension* app_extension_;
 
+  // Information about the language the page is in and has been translated to.
+  LanguageState language_state_;
+
   // ---------------------------------------------------------------------------
 
   DISALLOW_COPY_AND_ASSIGN(TabContents);