Expose the list of selected variations in the about:versions page in debug mode.

BUG=144713
TEST=In a Debug build, go to about:version. There should be a list of Variations in the page. In a Release build, ensure that the same page does not contain such text.


Review URL: https://chromiumcodereview.appspot.com/10868082

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@154067 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 92 insertions, 2 deletions

diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index 0fb35bc..5e10328 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -6413,6 +6413,9 @@ Keep your key file in a safe place. You will need it to create new versions of y
       <message name="IDS_ABOUT_VERSION_PATH_NOTFOUND" desc="label for the non-existent path on the about:version page">
         No such file or directory
       </message>
+      <message name="IDS_ABOUT_VERSION_VARIATIONS" desc="label for the variations list on the about:version page">
+        Variations
+      </message>
 
       <!-- JavaScript Dialog Box strings -->
       <message name="IDS_JAVASCRIPT_ALERT_DEFAULT_TITLE" desc="Title for JavaScript alert originating from a webpage if there is no hostname to display">
diff --git a/chrome/browser/resources/about_version.html b/chrome/browser/resources/about_version.html
index 1b71053..45ab5b2 100644
--- a/chrome/browser/resources/about_version.html
+++ b/chrome/browser/resources/about_version.html
@@ -14,6 +14,8 @@ about:version template page
 <if expr="pp_ifdef('android')">
     <link rel="stylesheet" href="about_version_android.css">
 </if>
+    <script src="chrome://resources/js/parse_html_subset.js"></script>
+    <script src="chrome://resources/js/util.js"></script>
     <script src="chrome://version/version.js"></script>
     <script src="chrome://version/strings.js"></script>
   </head>
@@ -66,6 +68,10 @@ about:version template page
         <tr><td class="label" valign="top" i18n-content="profile_path_name"></td>
             <td class="version" id="profile_path" i18n-content="profile_path"></td>
         </tr>
+        <tr id="variations-section">
+            <td class="label" valign="top" i18n-content="variations_name"></td>
+            <td class="version" id="variations-list"></td>
+        </tr>
       </table>
     </div>
     <script src="chrome://resources/js/i18n_template.js"></script>
diff --git a/chrome/browser/resources/about_version.js b/chrome/browser/resources/about_version.js
index 30ad114..88417fe 100644
--- a/chrome/browser/resources/about_version.js
+++ b/chrome/browser/resources/about_version.js
@@ -2,13 +2,26 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+/**
+ * Callback from the backend with the list of variations to display.
+ * This call will build the variations section of the version page, or hide that
+ * section if there are none to display.
+ * @param {!Array.<string>} variationsList The list of variations.
+ */
+function returnVariationsList(variationsList) {
+  $('variations-section').hidden = !variationsList.length;
+  $('variations-list').appendChild(
+      parseHtmlSubset(variationsList.join('<br>'), ['BR']));
+}
+
 /* All the work we do onload. */
 function onLoadWork() {
   // This is the javascript code that processes the template:
   var input = new JsEvalContext(templateData);
-  var output = document.getElementById('t');
+  var output = $('t');
   jstProcess(input, output);
+
+  chrome.send('requestVariationsList');
 }
 
 document.addEventListener('DOMContentLoaded', onLoadWork);
-
diff --git a/chrome/browser/ui/webui/about_ui.cc b/chrome/browser/ui/webui/about_ui.cc
index 73460ad..15d0e03 100644
--- a/chrome/browser/ui/webui/about_ui.cc
+++ b/chrome/browser/ui/webui/about_ui.cc
@@ -18,11 +18,13 @@
 #include "base/json/json_writer.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/memory/singleton.h"
+#include "base/metrics/field_trial.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/metrics/stats_table.h"
 #include "base/path_service.h"
 #include "base/string_number_conversions.h"
 #include "base/string_piece.h"
+#include "base/string_split.h"
 #include "base/string_util.h"
 #include "base/stringprintf.h"
 #include "base/threading/thread.h"
@@ -53,6 +55,7 @@
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_ui.h"
+#include "content/public/browser/web_ui_message_handler.h"
 #include "content/public/common/content_client.h"
 #include "content/public/common/process_type.h"
 #include "googleurl/src/gurl.h"
@@ -1110,6 +1113,11 @@ std::string AboutVersionStrings(DictionaryValue* localized_strings,
   }
   ChromeWebUIDataSource::SetFontAndTextDirection(localized_strings);
 
+#if !defined(NDEBUG)
+  localized_strings->SetString("variations_name",
+      l10n_util::GetStringUTF16(IDS_ABOUT_VERSION_VARIATIONS));
+#endif
+
   std::string data;
   jstemplate_builder::AppendJsonJS(localized_strings, &data);
   return data;
@@ -1289,6 +1297,64 @@ void ChromeOSAboutVersionHandler::OnVersion(
 
 #endif
 
+class VersionDOMHandler : public content::WebUIMessageHandler {
+ public:
+  VersionDOMHandler();
+  virtual ~VersionDOMHandler();
+
+  // content::WebUIMessageHandler implementation.
+  virtual void RegisterMessages() OVERRIDE;
+
+  // Callback for the "requestVariationsList" message. This requests the list of
+  // variations from the client and sends it to the frontend.
+  void HandleRequestVariationsList(const ListValue* args);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(VersionDOMHandler);
+};
+
+VersionDOMHandler::VersionDOMHandler() {
+}
+
+VersionDOMHandler::~VersionDOMHandler() {
+}
+
+void VersionDOMHandler::RegisterMessages() {
+  web_ui()->RegisterMessageCallback(
+      "requestVariationsList",
+      base::Bind(&VersionDOMHandler::HandleRequestVariationsList,
+      base::Unretained(this)));
+}
+
+void VersionDOMHandler::HandleRequestVariationsList(const ListValue* args) {
+  scoped_ptr<ListValue> variations_list(new ListValue());
+#if !defined(NDEBUG)
+  std::vector<std::string> variations;
+  std::string variation_state;
+  base::FieldTrialList::StatesToString(&variation_state);
+
+  std::vector<std::string> tokens;
+  base::SplitString(variation_state,
+                    base::FieldTrialList::kPersistentStringSeparator,
+                    &tokens);
+  // Since StatesToString appends a separator at the end, SplitString will
+  // append an extra empty string in the vector. Drop it. There should
+  // always be an even number of tokens left.
+  tokens.pop_back();
+  DCHECK_EQ(0U, tokens.size() % 2);
+  for (size_t i = 0; i < tokens.size(); i += 2)
+    variations.push_back(tokens[i] + ":" + tokens[i + 1]);
+
+  for (std::vector<std::string>::const_iterator it = variations.begin();
+      it != variations.end(); ++it) {
+    variations_list->Append(Value::CreateStringValue(*it));
+  }
+#endif
+  // In release mode, this will return an empty list to clear the section.
+  web_ui()->CallJavascriptFunction("returnVariationsList",
+                                   *variations_list.release());
+}
+
 }  // namespace
 
 // AboutUIHTMLSource ----------------------------------------------------------
@@ -1397,6 +1463,8 @@ AboutUI::AboutUI(content::WebUI* web_ui, const std::string& name)
   ChromeURLDataManager::AddDataSource(profile, theme);
 #endif
 
+  web_ui->AddMessageHandler(new VersionDOMHandler());
+
   ChromeURLDataManager::DataSource* source =
       new AboutUIHTMLSource(name, profile);
   if (source) {