Hook up PA_LOG() logs to chrome://proximity-auth WebUI.

BUG=409158
TEST=manual

Review URL: https://codereview.chromium.org/1135293002

Cr-Commit-Position: refs/heads/master@{#329877}

components/proximity_auth/logging/log_buffer.cc

@@ -37,16 +37,26 @@ LogBuffer* LogBuffer::GetInstance() {
   return &g_log_buffer.Get();
 }
 
+void LogBuffer::AddObserver(Observer* observer) {
+  observers_.AddObserver(observer);
+}
+
+void LogBuffer::RemoveObserver(Observer* observer) {
+  observers_.RemoveObserver(observer);
+}
+
 void LogBuffer::AddLogMessage(const LogMessage& log_message) {
   // Note: We may want to sort the messages by timestamp if there are cases
   // where logs are not added chronologically.
   log_messages_.push_back(log_message);
   if (log_messages_.size() > MaxBufferSize())
     log_messages_.pop_front();
+  FOR_EACH_OBSERVER(Observer, observers_, OnLogMessageAdded(log_message));
 }
 
 void LogBuffer::Clear() {
   log_messages_.clear();
+  FOR_EACH_OBSERVER(Observer, observers_, OnLogBufferCleared());
 }
 
 size_t LogBuffer::MaxBufferSize() const {

components/proximity_auth/logging/log_buffer.h

@@ -9,6 +9,7 @@
 
 #include "base/logging.h"
 #include "base/macros.h"
+#include "base/observer_list.h"
 #include "base/time/time.h"
 
 namespace proximity_auth {
@@ -33,12 +34,25 @@ class LogBuffer {
                logging::LogSeverity severity);
   };
 
+  class Observer {
+   public:
+    // Called when a new message is added to the log buffer.
+    virtual void OnLogMessageAdded(const LogMessage& log_message) = 0;
+
+    // Called when all messages in the log buffer are cleared.
+    virtual void OnLogBufferCleared() = 0;
+  };
+
   LogBuffer();
   ~LogBuffer();
 
   // Returns the global instance.
   static LogBuffer* GetInstance();
 
+  // Adds and removes log buffer observers.
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
   // Adds a new log message to the buffer. If the number of log messages exceeds
   // the maximum, then the earliest added log will be removed.
   void AddLogMessage(const LogMessage& log_message);
@@ -56,6 +70,9 @@ class LogBuffer {
   // The messages currently in the buffer.
   std::list<LogMessage> log_messages_;
 
+  // List of observers.
+  ObserverList<Observer> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(LogBuffer);
 };
 

components/proximity_auth/webui/proximity_auth_ui.cc

@@ -33,6 +33,9 @@ ProximityAuthUI::ProximityAuthUI(content::WebUI* web_ui)
   source->AddResourcePath("device-list.html",
                           IDR_PROXIMITY_AUTH_DEVICE_LIST_HTML);
   source->AddResourcePath("device-list.js", IDR_PROXIMITY_AUTH_DEVICE_LIST_JS);
+  source->AddResourcePath("log-buffer.html",
+                          IDR_PROXIMITY_AUTH_LOG_BUFFER_HTML);
+  source->AddResourcePath("log-buffer.js", IDR_PROXIMITY_AUTH_LOG_BUFFER_JS);
 
   content::BrowserContext* browser_context =
       web_ui->GetWebContents()->GetBrowserContext();

components/proximity_auth/webui/proximity_auth_webui_handler.cc

@@ -4,15 +4,85 @@
 
 #include "components/proximity_auth/webui/proximity_auth_webui_handler.h"
 
+#include "base/bind.h"
+#include "base/i18n/time_formatting.h"
+#include "base/values.h"
+#include "content/public/browser/web_ui.h"
+
 namespace proximity_auth {
 
+namespace {
+
+// Keys in the JSON representation of a log message.
+const char kLogMessageTextKey[] = "text";
+const char kLogMessageTimeKey[] = "time";
+const char kLogMessageFileKey[] = "file";
+const char kLogMessageLineKey[] = "line";
+const char kLogMessageSeverityKey[] = "severity";
+
+// Converts |log_message| to a raw dictionary value used as a JSON argument to
+// JavaScript functions.
+scoped_ptr<base::DictionaryValue> LogMessageToDictionary(
+    const LogBuffer::LogMessage& log_message) {
+  scoped_ptr<base::DictionaryValue> dictionary(new base::DictionaryValue());
+  dictionary->SetString(kLogMessageTextKey, log_message.text);
+  dictionary->SetString(kLogMessageTimeKey,
+                        base::TimeFormatTimeOfDay(log_message.time));
+  dictionary->SetString(kLogMessageFileKey, log_message.file);
+  dictionary->SetInteger(kLogMessageLineKey, log_message.line);
+  dictionary->SetInteger(kLogMessageSeverityKey,
+                         static_cast<int>(log_message.severity));
+  return dictionary.Pass();
+}
+
+}  // namespace
+
 ProximityAuthWebUIHandler::ProximityAuthWebUIHandler() {
+  LogBuffer::GetInstance()->AddObserver(this);
 }
 
 ProximityAuthWebUIHandler::~ProximityAuthWebUIHandler() {
+  LogBuffer::GetInstance()->RemoveObserver(this);
 }
 
 void ProximityAuthWebUIHandler::RegisterMessages() {
+  web_ui()->RegisterMessageCallback(
+      "clearLogBuffer", base::Bind(&ProximityAuthWebUIHandler::ClearLogBuffer,
+                                   base::Unretained(this)));
+
+  web_ui()->RegisterMessageCallback(
+      "getLogMessages", base::Bind(&ProximityAuthWebUIHandler::GetLogMessages,
+                                   base::Unretained(this)));
+}
+
+void ProximityAuthWebUIHandler::OnLogMessageAdded(
+    const LogBuffer::LogMessage& log_message) {
+  scoped_ptr<base::DictionaryValue> dictionary =
+      LogMessageToDictionary(log_message);
+  web_ui()->CallJavascriptFunction("LogBufferInterface.onLogMessageAdded",
+                                   *dictionary);
+}
+
+void ProximityAuthWebUIHandler::OnLogBufferCleared() {
+  web_ui()->CallJavascriptFunction("LogBufferInterface.onLogBufferCleared");
+}
+
+void ProximityAuthWebUIHandler::GetLogMessages(const base::ListValue* args) {
+  base::ListValue json_logs;
+  auto logs = LogBuffer::GetInstance()->logs();
+  std::transform(logs->begin(), logs->end(), json_logs.begin(),
+                 [](const LogBuffer::LogMessage& log) {
+                   return LogMessageToDictionary(log).release();
+                 });
+
+  web_ui()->CallJavascriptFunction("LogBufferInterface.onGotLogMessages",
+                                   json_logs);
+}
+
+void ProximityAuthWebUIHandler::ClearLogBuffer(const base::ListValue* args) {
+  // The OnLogBufferCleared() observer function will be called after the buffer
+  // is cleared.
+  LogBuffer::GetInstance()->Clear();
 }
 
 }  // namespace proximity_auth

components/proximity_auth/webui/proximity_auth_webui_handler.h

@@ -5,22 +5,36 @@
 #ifndef COMPONENTS_PROXIMITY_AUTH_WEBUI_PROXIMITY_AUTH_WEBUI_HANDLER_H_
 #define COMPONENTS_PROXIMITY_AUTH_WEBUI_PROXIMITY_AUTH_WEBUI_HANDLER_H_
 
+#include "components/proximity_auth/logging/log_buffer.h"
 #include "content/public/browser/web_ui_message_handler.h"
 
+namespace base {
+class ListValue;
+}
+
 namespace proximity_auth {
 
 class ProximityAuthService;
 
 // Handles messages from the chrome://proximity-auth page.
-class ProximityAuthWebUIHandler : public content::WebUIMessageHandler {
+class ProximityAuthWebUIHandler : public content::WebUIMessageHandler,
+                                  public LogBuffer::Observer {
  public:
   ProximityAuthWebUIHandler();
   ~ProximityAuthWebUIHandler() override;
 
-  // content::WebUIMessageHandler implementation.
+  // content::WebUIMessageHandler:
   void RegisterMessages() override;
 
  private:
+  // LogBuffer::Observer:
+  void OnLogMessageAdded(const LogBuffer::LogMessage& log_message) override;
+  void OnLogBufferCleared() override;
+
+  // Message handler callbacks.
+  void GetLogMessages(const base::ListValue* args);
+  void ClearLogBuffer(const base::ListValue* args);
+
   DISALLOW_COPY_AND_ASSIGN(ProximityAuthWebUIHandler);
 };
 

components/proximity_auth/webui/resources/log-buffer.html

+<link href="chrome://resources/polymer/polymer/polymer.html" rel="import">
+<polymer-element name="log-buffer">
+  <template></template>
+  <script src="log-buffer.js"></script>
+</polymer-element>

components/proximity_auth/webui/resources/log-buffer.js

+// Copyright 2015 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.
+
+Polymer('log-buffer', {
+  publish: {
+    /**
+     * List of displayed logs.
+     * @type {?Array.<{{
+     *    text: string,
+     *    time: string,
+     *    file: string,
+     *    line: number,
+     *    severity: number,
+     * }}>} LogMessage
+     */
+    logs: null,
+  },
+
+  /**
+   * Called when an instance is created.
+   */
+  created: function() {
+    this.logs = [];
+    // We assume that only one instance of log-buffer is ever created.
+    LogBufferInterface = this;
+    chrome.send('getLogMessages');
+  },
+
+  // Clears the native LogBuffer.
+  clearLogs: function() {
+    chrome.send('clearLogBuffer');
+  },
+
+  // Handles when a new log message is added.
+  onLogMessageAdded: function(log) {
+    this.logs.push(log);
+  },
+
+  // Handles when the logs are cleared.
+  onLogBufferCleared: function() {
+    this.logs = [];
+  },
+
+  // Handles when the logs are returned in response to the 'getLogMessages'
+  // request.
+  onGotLogMessages: function(logs) {
+    this.logs = logs;
+  }
+});
+
+// Interface with the native WebUI component for LogBuffer events. The functions
+// contained in this object will be invoked by the browser for each operation
+// performed on the native LogBuffer.
+LogBufferInterface = {
+  /**
+   * Called when a new log message is added.
+   * @type {function(LogMessage)}
+   */
+  onLogMessageAdded: function(log) {},
+
+  /**
+   * Called when the log buffer is cleared.
+   * @type {function()}
+   */
+  onLogBufferCleared: function() {},
+
+  /**
+   * Called in response to chrome.send('getLogMessages') with the log messages
+   * currently in the buffer.
+   * @type {function(Array.<LogMessage>)}
+   */
+  onGotLogMessages: function(messages) {},
+};

components/proximity_auth/webui/resources/log-panel.html

@@ -2,6 +2,7 @@
 <link href="chrome://resources/polymer/core-toolbar/core-toolbar.html" rel="import">
 <link href="chrome://resources/polymer/paper-icon-button/paper-icon-button.html" rel="import">
 <link href="chrome://resources/polymer/core-icons/communication-icons.html" rel="import">
+<link href="log-buffer.html" rel="import">
 
 <polymer-element name="log-panel" layout vertical>
   <template>
@@ -28,8 +29,18 @@
         padding: 15px 30px;
       }
 
+      .list-item[severity="1"] {
+        background-color: #fffcef;
+        color: #312200;
+      }
+
+      .list-item[severity="2"] {
+        background-color: #fff1f1;
+        color: #ef0000;
+      }
+
       .item-metadata {
-        color: rgb(153, 153, 153);
+        color: #888888;
         font-size: 10px;
       }
 
@@ -45,18 +56,19 @@
     </style>
 
     <core-toolbar layout horizontal end-justified center
-                  on-click="{{clearLogs}}">
+                  on-click="{{clearLogs_}}">
       <paper-icon-button icon="communication:clear-all"></paper-icon-button>
     </core-toolbar>
 
+    <log-buffer id='logBuffer' logs="{{logs}}"></log-buffer>
     <div id="list" flex>
       <template repeat="{{log in logs}}">
         <div class="list-item {{ {selected: log.selected} | tokenList }}"
-             on-click={{itemClick}}>
+             on-click={{itemClick}} severity="{{log.severity}}">
           <div class="item-metadata" layout horizontal>
-            <div>14:23:50</div>
+            <div>{{log.time}}</div>
             <div flex></div>
-            <div>proximity_auth_class.cc:123</div>
+            <div>{{stripPath_(log.file)}}:{{log.line}}</div>
           </div>
           <pre class="item-log" flex>{{log.text}}</pre>
         </div>

components/proximity_auth/webui/resources/log-panel.js

@@ -16,202 +16,24 @@ Polymer('log-panel', {
   },
 
   /**
-   * Called when an instance is created.
-   */
-  created: function() {
-    this.logs = [
-      { text: 'sh: missing ]' },
-      { text: 'Starting Mount filesystems on boot [ OK ]' },
-      { text: 'Starting Populate /dev filesystem [ OK ]' },
-      { text: 'Stopping Populate /dev filesystem [ OK ]' },
-      { text: 'Starting Create /var/run/ccache [ OK ]' },
-      { text: 'Starting Populate and link to /run filesystem [ OK ]' },
-      { text: 'Starting Create /run/credentials-cache [ OK ]' },
-      { text: 'Stopping Create /var/run/ccache [ OK ]' },
-      { text: 'Stopping Populate and link to /run filesystem [ OK ]' },
-      { text: 'Stopping Create /run/credentials-cache [ OK ]' },
-      { text: 'Starting Signal sysvinit that the rootfs is mounted [ OK ]' },
-      { text: 'Starting Clean /tmp directory [ OK ]' },
-      { text: 'Stopping Track if upstart is running in a container [ OK ]' },
-      { text: 'Starting mount available cgroup filesystems [ OK ]' },
-      { text: 'Stopping Clean /tmp directory [ OK ]' },
-      { text: 'Starting Initialize or finalize resolvconf [ OK ]' },
-      { text: 'mount: none already mounted or /dev/cgroup/cpu busy' },
-      { text: 'Starting Set custom IMA policy [ OK ]' },
-      { text: 'Stopping Set custom IMA policy [ OK ]' },
-      { text: 'Starting Bridge udev events into upstart [ OK ]' },
-      { text: 'Starting detecthammer security monitoring daemon [ OK ]' },
-      { text: 'Starting linhelm security monitoring daemon [ OK ]' },
-      { text: 'Starting Fetch otp over bluetooth on demand [ OK ]' },
-      { text: 'Starting device node and kernel event manager [ OK ]' },
-      { text: 'Starting Enabling additional executable binary formats [ OK ]' },
-      { text: 'Starting flush early job output to logs [ OK ]' },
-      { text: 'Stopping Mount filesystems on boot [ OK ]' },
-      { text: 'Starting NFSv4 id <-> name mapper [ OK ]' },
-      { text: 'Stopping flush early job output to logs [ OK ]' },
-      { text: 'Starting load modules from /etc/modules [ OK ]' },
-      { text: 'Starting load modules from /etc/modules [ OK ]' },
-      { text: 'Starting log initial device creation [ OK ]' },
-      { text: 'Starting D-Bus system message bus [ OK ]' },
-      { text: 'Stopping load modules from /etc/modules [ OK ]' },
-      { text: 'Stopping load modules from /etc/modules [ OK ]' },
-      { text: 'Starting Uncomplicated firewall [ OK ]' },
-      { text: 'Starting Bridge file events into upstart [ OK ]' },
-      { text: 'Starting bluetooth daemon [ OK ]' },
-      { text: 'Starting SystemD login management service [ OK ]' },
-      { text: 'Starting system logging daemon [ OK ]' },
-      { text: 'Starting configure network device security [ OK ]' },
-      { text: 'Starting configure network device security [ OK ]' },
-      { text: 'Stopping cold plug devices [ OK ]' },
-      { text: 'Starting configure network device security [ OK ]' },
-      { text: 'Starting CUPS printing spooler/server [ OK ]' },
-      { text: 'Starting configure network device [ OK ]' },
-      { text: 'Starting Mount network filesystems [ OK ]' },
-      { text: 'Starting Upstart job to start rpcbind on boot only [ OK ]' },
-      { text: 'Starting Failsafe Boot Delay [ OK ]' },
-      { text: 'Stopping log initial device creation [ OK ]' },
-      { text: 'Stopping Upstart job to start rpcbind on boot only [ OK ]' },
-      { text: 'Starting load fallback graphics devices [ OK ]' },
-      { text: 'Starting configure network device security [ OK ]' },
-      { text: 'Starting configure network device [ OK ]' },
-      { text: 'Stopping load fallback graphics devices [ OK ]' },
-      { text: 'Stopping Failsafe Boot Delay [ OK ]' },
-      { text: 'Stopping Mount network filesystems [ OK ]' },
-      { text: 'Starting System V initialisation compatibility [ OK ]' },
-      { text: 'Starting configure virtual network devices [ OK ]' },
-      { text: 'Initializing random number generator...         [ OK ]' },
-      { text: 'Setting up X socket directories...         [ OK ]' },
-      { text: 'Starting configure network device [ OK ]' },
-      { text: 'Starting modem connection manager [ OK ]' },
-      { text: 'Starting configure network device security [ OK ]' },
-      { text: 'Starting RPC portmapper replacement [ OK ]' },
-      { text: 'Stopping System V initialisation compatibility [ OK ]' },
-      { text: 'Starting Create /var/run/ccache [ OK ]' },
-      { text: 'Stopping Create /var/run/ccache [ OK ]' },
-      { text: 'Starting Monitor for unauthorized access to cookies. [ OK ]' },
-      { text: 'Starting System V runlevel compatibility [ OK ]' },
-      { text: 'Starting anac(h)ronistic cron [ OK ]' },
-      { text: 'Starting ACPI daemon [ OK ]' },
-      { text: 'Starting regular background program processing daemon [ OK ]' },
-      { text: 'Starting deferred execution scheduler [ OK ]' },
-      { text: 'Starting Run the nvidia-updater Upstart task before the ' +
-              'goobuntu-updater Upstart task [ OK ]' },
-      { text: 'Starting build kernel modules for current kernel [ OK ]' },
-      { text: 'Starting CPU interrupts balancing daemon [ OK ]' },
-      { text: 'Starting rpcsec_gss daemon [ OK ]' },
-      { text: 'Starting NSM status monitor [ OK ]' },
-      { text: 'Stopping anac(h)ronistic cron [ OK ]' },
-      { text: 'Starting Run the nvidia-updater during startup [ OK ]' },
-      { text: 'Starting regular background program processing daemon [ OK ]' },
-      { text: 'Starting KVM [ OK ]' },
-      { text: 'Starting automatic crash report generation [ OK ]' },
-      { text: 'Starting Automounter [ OK ]' },
-      { text: 'Stopping Restore Sound Card State [ OK ]' },
-      { text: 'Starting libvirt daemon [ OK ]' },
-      { text: 'gdm start/starting' },
-      { text: 'initctl: Unknown job: kdm' },
-      { text: 'lightdm start/starting' },
-      { text: 'initctl: Unknown job: lxdm' },
-      { text: 'Starting Bridge socket events into upstart [ OK ]' },
-      { text: 'Skipping profile in /etc/apparmor.d/disable: usr.bin.firefox' },
-      { text: 'Starting AppArmor profiles         [ OK ]' },
-      { text: 'Checking for available NVIDIA updates ...' },
-      { text: 'Starting audit daemon auditd         [ OK ]' },
-      { text: 'Starting Dropbear SSH server: [abort] NO_START is not ' +
-              'set to zero in /etc/default/dropbear' },
-      { text: 'Starting logs-exporterd         [ OK ]' },
-      { text: 'Starting Machine Check Exceptions decoder: mcelog.' },
-      { text: 'ERROR: [Errno -2] Name or service not known' },
-      { text: '2015-04-01 13:12:35,580:INFO:Daemon process started in the ' +
-              'background, logging to ' +
-              '"/tmp/chrome_remote_desktop_20150401_131235_3BiEyp"' },
-      { text: 'Using host_id: cd1af87e-488c-38ec-6b84-40e028bbf174' },
-      { text: 'Launching X server and X session.' },
-      { text: 'Starting NTP server ntpd         [ OK ]' },
-      { text: 'Not starting internet superserver: no services enabled' },
-      { text: 'Starting OpenCryptoki PKCS#11 slot daemon: pkcsslotd.' },
-      { text: 'Starting OSS Proxy Daemon osspd         [ OK ]' },
-      { text: 'Starting /usr/bin/Xvfb-randr on display :20' },
-      { text: 'Starting network connection manager [ OK ]' },
-      { text: 'INFO: Configuring network-manager from upstart' },
-      { text: '/proc/self/fd/9: line 6: INFO: Configuring network-manager ' +
-              'from upstart: command not found' },
-      { text: 'Updating connection SNAX' },
-      { text: 'Xvfb is active.' },
-      { text: 'Completed successfully' },
-      { text: 'INFO: Success' },
-      { text: '/proc/self/fd/9: line 6: INFO: Success: command not found' },
-      { text: 'Starting Postfix Mail Transport Agent postfix         [ OK ]' },
-      { text: 'Stopping build kernel modules for current kernel [ OK ]' },
-      { text: 'Launching host process' },
-      { text: 'Stopping Run the nvidia-updater during startup [ OK ]' },
-      { text: 'Stopping Run the nvidia-updater Upstart task before the ' +
-              'goobuntu-updater Upstart task [ OK ]' },
-      { text: 'Waiting up to 60s for the hostname ...' },
-      { text: 'Recovering schroot sessions         [ OK ]' },
-      { text: '[33m*39;49m Not starting S.M.A.R.T. daemon smartd, disabled ' +
-              'via /etc/default/smartmontools' },
-      { text: 'Starting OpenBSD Secure Shell server...         [ OK ]' },
-      { text: 'No response from daemon. It may have crashed, or may still ' +
-              'be running in the background.' },
-      { text: 'Host ready to receive connections.' },
-      { text: 'Log file: /tmp/chrome_remote_desktop_20150401_131235_3BiEyp' },
-      { text: 'Starting VirtualBox kernel modules         [ OK ]' },
-      { text: 'saned disabled; edit /etc/default/saned' },
-      { text: 'Restoring resolver state...         [ OK ]' },
-      { text: 'The hostname has not changed' },
-      { text:
-        'access-control-allow-origin:*\n        ' +
-        'cache-control:public, max-age=600\n        ' +
-        'date:Thu, 16 Apr 2015 21:15:23 GMT\n        ' +
-        'etag:"nhb8IQ"\n        ' +
-        'expires:Thu, 16 Apr 2015 21:25:23 GMT\n        ' +
-        'server:Google Frontend\n        ' +
-        'status:304\n        ' +
-        'x-google-appengine-appid:s~polymer-project\n        ' +
-        'x-google-appengine-module:default\n        ' +
-        'x-google-appengine-version:2015-04-13\n        ' +
-        'x-google-backends:/gns/project/apphosting/appserver/prod-appengine' +
-        '/ic/prod-appengine.remote-ib.appserver/380,icbie6.prod.google.com:' +
-        '4489,/bns/ic/borg/ic/bns/apphosting/prod-appengine.edge.frontend/2' +
-        '30,ibk19:6599,/bns/ib/borg/ib/bns/gfe-prod/shared-gfe_31_silos/1.g' +
-        'fe,icna18:9845\n        ' +
-        'x-google-dos-service-trace:main:apphosting,dasher:' +
-        'apphosting\n        ' +
-        'x-google-gfe-request-trace:icna18:9845,ibk19:6599,/bns/ic/borg/ic/' +
-        'bns/apphosting/prod-appengine.edge.frontend/230,ibk19:6599,icna18:' +
-        '9845\n        ' +
-        'x-google-gfe-response-code-details-trace:response_code_set_by_back' +
-        'end,response_code_set_by_backend\n        ' +
-        'x-google-gfe-service-trace:apphosting,dasher_zoo_responder,apphost' +
-        'ing\n        ' +
-        'x-google-gslb-service:apphosting\n        ' +
-        'x-google-netmon-label:/bns/ic/borg/ic/bns/apphosting/prod-appengin' +
-        'e.edge.frontend/230\n        ' +
-        'x-google-service:apphosting,apphosting\n' },
-      { text: 'goobuntu-updater configuration: ARGS="--init ' +
-              '--only-if-forced --verbose" BLOCK_BOOT=false' },
-      { text: 'Running goobuntu-updater ...' },
-      { text: 'Starting GNOME Display Manager [ OK ]' },
-      { text: 'No apache MPM package installed' },
-      { text: 'Starting Unblock the restart of the gdm display ' +
-              'manager when it stops by emitting the ' +
-              'nvidia-updater-unblock-gdm-start event [ OK ]' },
-      { text: 'Stopping GNOME Display Manager [ OK ]' },
-    ];
-  },
-
-  /**
-   * Stores the logs that are cleared.
-   * @type {Array.<Log>}
+   * @type {boolean}
    * @private
    */
-  prevLogs_: null,
+  isScrollAtBottom_: true,
 
   /**
    * Called after the Polymer element is initialized.
    */
   ready: function() {
+    this.$.list.onscroll = this.onScroll_.bind(this);
+    this.async(this.scrollToBottom_);
+  },
+
+  /**
+   * Called when the list of logs change.
+   */
+  logsChanged: function(oldValue, newValue) {
+    if (this.isScrollAtBottom_)
       this.async(this.scrollToBottom_);
   },
 
@@ -219,11 +41,18 @@ Polymer('log-panel', {
    * Clears the logs.
    * @private
    */
-  clearLogs: function() {
-    var prevLogs = this.logs;
-    this.logs = this.prevLogs;
-    this.prevLogs = prevLogs;
-    this.async(this.scrollToBottom_);
+  clearLogs_: function() {
+    this.$.logBuffer.clearLogs();
+  },
+
+  /**
+   * Event handler when the list is scrolled.
+   * @private
+   */
+  onScroll_: function() {
+    var list = this.$.list;
+    this.isScrollAtBottom_ =
+        list.scrollTop + list.offsetHeight == list.scrollHeight;
   },
 
   /**
@@ -233,4 +62,14 @@ Polymer('log-panel', {
   scrollToBottom_: function() {
     this.$.list.scrollTop = this.$.list.scrollHeight;
   },
+
+  /**
+   * @param {string} filename
+   * @return {string} The filename stripped of its preceeding path.
+   * @private
+   */
+  stripPath_: function(filename) {
+    var directories = filename.split('/');
+    return directories[directories.length - 1];
+  },
 });

components/resources/proximity_auth_resources.grdp

@@ -18,4 +18,8 @@
            file="../proximity_auth/webui/resources/device-list.html" flattenhtml="true" allowexternalscript="true" type="BINDATA" />
   <include name="IDR_PROXIMITY_AUTH_DEVICE_LIST_JS"
            file="../proximity_auth/webui/resources/device-list.js" flattenhtml="true" allowexternalscript="true" type="BINDATA" />
+  <include name="IDR_PROXIMITY_AUTH_LOG_BUFFER_HTML"
+           file="../proximity_auth/webui/resources/log-buffer.html" flattenhtml="true" allowexternalscript="true" type="BINDATA" />
+  <include name="IDR_PROXIMITY_AUTH_LOG_BUFFER_JS"
+           file="../proximity_auth/webui/resources/log-buffer.js" flattenhtml="true" allowexternalscript="true" type="BINDATA" />
 </grit-part>