Add 'translate_recent_target' to chrome://translate-internals

This should make it easier to debug Translate internals.

UI changes:

1. Add 'translate_recent_target' to the Preferences dump in the
   translate-internals page.

2. Add a box for the user to enter a new value for 'translate_recent_target',
   and an 'update' button. When the user clicks the button, the preference is
   updated.

Bug: 855176
Cq-Include-Trybots: luci.chromium.try:closure_compilation
Change-Id: I97437c792c8b6efb73bdb6d1c21f05c5ffff7d8a
Reviewed-on: https://chromium-review.googlesource.com/1110739Reviewed-by: anthonyvd <anthonyvd@chromium.org>
Reviewed-by: Hajime Hoshi <hajimehoshi@chromium.org>
Commit-Queue: Nicolas Ouellet-Payeur <nicolaso@chromium.org>
Cr-Commit-Position: refs/heads/master@{#570747}

chrome/browser/resources/translate_internals/prefs.html

@@ -43,4 +43,10 @@ found in the LICENSE file.
     <h2 id="override-variations-country">Override Variations Country</h2>
     <p id="country-override"></p>
   </section>
+  <section>
+    <h2 id="override-recent-target">
+      Override <code>translate_recent_target</code>
+    </h2>
+    <p id="recent-override"></p>
+  </section>
 </div>

chrome/browser/resources/translate_internals/translate_internals.js

@@ -212,6 +212,18 @@ cr.define('cr.translateInternals', function() {
     p.appendChild(createDismissingButton(
         chrome.send.bind(null, 'removePrefItem', ['too_often_denied'])));
 
+    if ('translate_recent_target' in detail) {
+      var recentTarget = detail['translate_recent_target'];
+
+      p = $('recent-override');
+
+      p.innerHTML = '';
+
+      appendTextFieldWithButton(p, recentTarget, function(value) {
+        chrome.send('setRecentTargetLanguage', [value]);
+      });
+    }
+
     p = document.querySelector('#prefs-dump p');
     var content = JSON.stringify(detail, null, 2);
     p.textContent = content;
@@ -264,18 +276,9 @@ cr.define('cr.translateInternals', function() {
            'with a new value received from the variations server when ' +
            'Chrome is updated.');
 
-      var input = document.createElement('input');
-      input.type = 'text';
-      input.value = country;
-
-      var button = document.createElement('button');
-      button.textContent = 'update';
-      button.addEventListener('click', function() {
-        chrome.send('overrideCountry', [input.value]);
-      }, false);
-      p.appendChild(input);
-      p.appendChild(document.createElement('br'));
-      p.appendChild(button);
+      appendTextFieldWithButton(p, country, function(value) {
+        chrome.send('overrideCountry', [value]);
+      });
 
       if ('update' in details && details['update']) {
         var div1 = document.createElement('div');
@@ -431,6 +434,32 @@ cr.define('cr.translateInternals', function() {
     tbody.appendChild(tr);
   }
 
+  /**
+   * Appends an <input type="text" /> and a button to `elt`, and sets the value
+   * of the <input> to `value`. When the button is clicked,
+   * `buttonClickCallback` is called with the value of the <input> field.
+   *
+   * @param {HTMLElement} elt Container element to append to.
+   * @param {string} value Initial value of the <input> element.
+   * @param {Function} buttonClickCallback Function to call when the button is
+   *                                       clicked.
+   */
+  function appendTextFieldWithButton(elt, value, buttonClickCallback) {
+    var input = document.createElement('input');
+    input.type = 'text';
+    input.value = value;
+
+    var button = document.createElement('button');
+    button.textContent = 'update';
+    button.addEventListener('click', function() {
+      buttonClickCallback(input.value);
+    }, false);
+
+    elt.appendChild(input);
+    elt.appendChild(document.createElement('br'));
+    elt.appendChild(button);
+  }
+
   /**
    * The callback entry point from the browser. This function will be
    * called by the browser.

chrome/browser/ui/webui/translate_internals/translate_internals_handler.cc

@@ -63,6 +63,10 @@ void TranslateInternalsHandler::RegisterMessages() {
       "removePrefItem",
       base::BindRepeating(&TranslateInternalsHandler::OnRemovePrefItem,
                           base::Unretained(this)));
+  web_ui()->RegisterMessageCallback(
+      "setRecentTargetLanguage",
+      base::BindRepeating(&TranslateInternalsHandler::OnSetRecentTargetLanguage,
+                          base::Unretained(this)));
   web_ui()->RegisterMessageCallback(
       "requestInfo",
       base::BindRepeating(&TranslateInternalsHandler::OnRequestInfo,
@@ -164,6 +168,24 @@ void TranslateInternalsHandler::OnRemovePrefItem(const base::ListValue* args) {
   SendPrefsToJs();
 }
 
+void TranslateInternalsHandler::OnSetRecentTargetLanguage(
+    const base::ListValue* args) {
+  content::WebContents* web_contents = web_ui()->GetWebContents();
+  Profile* profile =
+      Profile::FromBrowserContext(web_contents->GetBrowserContext());
+  PrefService* prefs = profile->GetOriginalProfile()->GetPrefs();
+  std::unique_ptr<translate::TranslatePrefs> translate_prefs(
+      ChromeTranslateClient::CreateTranslatePrefs(prefs));
+
+  std::string new_value;
+  if (!args->GetString(0, &new_value))
+    return;
+
+  translate_prefs->SetRecentTargetLanguage(new_value);
+
+  SendPrefsToJs();
+}
+
 void TranslateInternalsHandler::OnOverrideCountry(const base::ListValue* args) {
   std::string country;
   if (args->GetString(0, &country)) {
@@ -199,6 +221,7 @@ void TranslateInternalsHandler::SendPrefsToJs() {
 
   static const char* keys[] = {
       prefs::kOfferTranslateEnabled,
+      translate::TranslatePrefs::kPrefTranslateRecentTarget,
       translate::TranslatePrefs::kPrefTranslateBlockedLanguages,
       translate::TranslatePrefs::kPrefTranslateSiteBlacklist,
       translate::TranslatePrefs::kPrefTranslateWhitelists,

chrome/browser/ui/webui/translate_internals/translate_internals_handler.h

@@ -59,6 +59,11 @@ class TranslateInternalsHandler : public content::WebUIMessageHandler,
   // when UI requests to remove an item in the preference.
   void OnRemovePrefItem(const base::ListValue* args);
 
+  // Handles the JavaScript message 'setRecentTargetLanguage'. This message is
+  // sent when the UI requests to change the 'translate_recent_target'
+  // preference.
+  void OnSetRecentTargetLanguage(const base::ListValue* args);
+
   // Handles the Javascript message 'overrideCountry'. This message is sent
   // when UI requests to override the stored country.
   void OnOverrideCountry(const base::ListValue* country);