Adds the ability to load JSON log files to about:net-internals.

Only works with logs created by the new "--log-net-log=file",
which writes NetLog events to the specified file, regardless
of other logging command line parameters.

Using "--log-net-log" without a file name will just write
NetLog events to VLOG(1), as before.

BUG=63687
TEST=None

Review URL: http://codereview.chromium.org/6025017

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@72567 0039d316-1c4b-4281-b951-d872f2087c98

10 files changed, 363 insertions, 43 deletions

diff --git a/chrome/browser/dom_ui/net_internals_ui.cc b/chrome/browser/dom_ui/net_internals_ui.cc
index 403eb5e..856c2b7 100644
--- a/chrome/browser/dom_ui/net_internals_ui.cc
+++ b/chrome/browser/dom_ui/net_internals_ui.cc
@@ -28,6 +28,9 @@
 #include "chrome/browser/net/url_fixer_upper.h"
 #include "chrome/browser/platform_util.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/shell_dialogs.h"
+#include "chrome/browser/tab_contents/tab_contents.h"
+#include "chrome/browser/tab_contents/tab_contents_view.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_version_info.h"
 #include "chrome/common/jstemplate_builder.h"
@@ -136,6 +139,7 @@ class NetInternalsHTMLSource : public ChromeURLDataManager::DataSource {
 // TODO(eroman): Can we start on the IO thread to begin with?
 class NetInternalsMessageHandler
     : public DOMMessageHandler,
+      public SelectFileDialog::Listener,
       public base::SupportsWeakPtr<NetInternalsMessageHandler> {
  public:
   NetInternalsMessageHandler();
@@ -150,12 +154,43 @@ class NetInternalsMessageHandler
   void CallJavascriptFunction(const std::wstring& function_name,
                               const Value* value);
 
+  // SelectFileDialog::Listener implementation
+  virtual void FileSelected(const FilePath& path, int index, void* params);
+  virtual void FileSelectionCanceled(void* params);
+
+  // The only callback handled on the UI thread.  As it needs to access fields
+  // from |dom_ui_|, it can't be called on the IO thread.
+  void OnLoadLogFile(const ListValue* list);
+
  private:
   class IOThreadImpl;
 
+  // Task run on the FILE thread to read the contents of a log file.  The result
+  // is then passed to IOThreadImpl's CallJavascriptFunction, which sends it
+  // back to the web page.  IOThreadImpl is used instead of the
+  // NetInternalsMessageHandler directly because it checks if the message
+  // handler has been destroyed in the meantime.
+  class ReadLogFileTask : public Task {
+   public:
+    ReadLogFileTask(IOThreadImpl* proxy, const FilePath& path);
+
+    virtual void Run();
+
+   private:
+    // IOThreadImpl implements existence checks already.  Simpler to reused them
+    // then to reimplement them.
+    scoped_refptr<IOThreadImpl> proxy_;
+
+    // Path of the file to open.
+    const FilePath path_;
+  };
+
   // This is the "real" message handler, which lives on the IO thread.
   scoped_refptr<IOThreadImpl> proxy_;
 
+  // Used for loading log files.
+  scoped_refptr<SelectFileDialog> select_log_file_dialog_;
+
   DISALLOW_COPY_AND_ASSIGN(NetInternalsMessageHandler);
 };
 
@@ -243,17 +278,17 @@ class NetInternalsMessageHandler::IOThreadImpl
       int result);
   virtual void OnCompletedConnectionTestSuite();
 
+  // Helper that executes |function_name| in the attached renderer.
+  // The function takes ownership of |arg|.  Note that this can be called from
+  // any thread.
+  void CallJavascriptFunction(const std::wstring& function_name, Value* arg);
+
  private:
   class CallbackHelper;
 
   // Helper that runs |method| with |arg|, and deletes |arg| on completion.
   void DispatchToMessageHandler(ListValue* arg, MessageHandler method);
 
-  // Helper that executes |function_name| in the attached renderer.
-  // The function takes ownership of |arg|.  Note that this can be called from
-  // any thread.
-  void CallJavascriptFunction(const std::wstring& function_name, Value* arg);
-
   // Adds |entry| to the queue of pending log entries to be sent to the page via
   // Javascript.  Must be called on the IO Thread.  Also creates a delayed task
   // that will call PostPendingEntries, if there isn't one already.
@@ -398,6 +433,8 @@ NetInternalsMessageHandler::~NetInternalsMessageHandler() {
     BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
         NewRunnableMethod(proxy_.get(), &IOThreadImpl::Detach));
   }
+  if (select_log_file_dialog_)
+    select_log_file_dialog_->ListenerDestroyed();
 }
 
 DOMMessageHandler* NetInternalsMessageHandler::Attach(DOMUI* dom_ui) {
@@ -408,8 +445,35 @@ DOMMessageHandler* NetInternalsMessageHandler::Attach(DOMUI* dom_ui) {
   return result;
 }
 
+void NetInternalsMessageHandler::FileSelected(
+    const FilePath& path, int index, void* params) {
+  select_log_file_dialog_.release();
+  BrowserThread::PostTask(
+      BrowserThread::FILE, FROM_HERE,
+      new ReadLogFileTask(proxy_.get(), path));
+}
+
+void NetInternalsMessageHandler::FileSelectionCanceled(void* params) {
+  select_log_file_dialog_.release();
+}
+
+void NetInternalsMessageHandler::OnLoadLogFile(const ListValue* list) {
+  // Only allow a single dialog at a time.
+  if (select_log_file_dialog_.get())
+    return;
+  select_log_file_dialog_ = SelectFileDialog::Create(this);
+  select_log_file_dialog_->SelectFile(
+      SelectFileDialog::SELECT_OPEN_FILE, string16(), FilePath(), NULL, 0,
+      FILE_PATH_LITERAL(""),
+      dom_ui_->tab_contents()->view()->GetTopLevelNativeWindow(), NULL);
+}
+
 void NetInternalsMessageHandler::RegisterMessages() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  // Only callback handled on UI thread.
+  dom_ui_->RegisterMessageCallback(
+      "loadLogFile",
+      NewCallback(this, &NetInternalsMessageHandler::OnLoadLogFile));
 
   dom_ui_->RegisterMessageCallback(
       "notifyReady",
@@ -471,6 +535,25 @@ void NetInternalsMessageHandler::CallJavascriptFunction(
 
 ////////////////////////////////////////////////////////////////////////////////
 //
+// NetInternalsMessageHandler::ReadLogFileTask
+//
+////////////////////////////////////////////////////////////////////////////////
+
+NetInternalsMessageHandler::ReadLogFileTask::ReadLogFileTask(
+    IOThreadImpl* proxy, const FilePath& path)
+    : proxy_(proxy), path_(path) {
+}
+
+void NetInternalsMessageHandler::ReadLogFileTask::Run() {
+  std::string file_contents;
+  if (!file_util::ReadFileToString(path_, &file_contents))
+    return;
+  proxy_->CallJavascriptFunction(L"g_browser.loadedLogFile",
+                                 new StringValue(file_contents));
+}
+
+////////////////////////////////////////////////////////////////////////////////
+//
 // NetInternalsMessageHandler::IOThreadImpl
 //
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/chrome/browser/net/chrome_net_log.cc b/chrome/browser/net/chrome_net_log.cc
index 58fe6ad..39ebe79 100644
--- a/chrome/browser/net/chrome_net_log.cc
+++ b/chrome/browser/net/chrome_net_log.cc
@@ -67,7 +67,8 @@ ChromeNetLog::ChromeNetLog()
 
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
   if (command_line.HasSwitch(switches::kLogNetLog)) {
-    net_log_logger_.reset(new NetLogLogger());
+    net_log_logger_.reset(new NetLogLogger(
+            command_line.GetSwitchValuePath(switches::kLogNetLog)));
     AddObserver(net_log_logger_.get());
   }
 }
diff --git a/chrome/browser/net/net_log_logger.cc b/chrome/browser/net/net_log_logger.cc
index bba75ca..1468e6f 100644
--- a/chrome/browser/net/net_log_logger.cc
+++ b/chrome/browser/net/net_log_logger.cc
@@ -4,11 +4,19 @@
 
 #include "chrome/browser/net/net_log_logger.h"
 
+#include <stdio.h>
+
+#include "base/file_util.h"
 #include "base/json/json_writer.h"
+#include "base/threading/thread_restrictions.h"
 #include "base/values.h"
 
-NetLogLogger::NetLogLogger()
+NetLogLogger::NetLogLogger(const FilePath &log_path)
     : ThreadSafeObserver(net::NetLog::LOG_ALL_BUT_BYTES) {
+  if (!log_path.empty()) {
+    base::ThreadRestrictions::ScopedAllowIO allow_io;
+    file_.Set(file_util::OpenFile(log_path, "w"));
+  }
 }
 
 NetLogLogger::~NetLogLogger() {}
@@ -21,8 +29,16 @@ void NetLogLogger::OnAddEntry(net::NetLog::EventType type,
   scoped_ptr<Value> value(net::NetLog::EntryToDictionaryValue(type, time,
                                                               source, phase,
                                                               params, true));
+  // Don't pretty print, so each JSON value occupies a single line, with no
+  // breaks (Line breaks in any text field will be escaped).  Using strings
+  // instead of integer identifiers allows logs from older versions to be
+  // loaded, though a little extra parsing has to be done when loading a log.
   std::string json;
-  base::JSONWriter::Write(value.get(), true, &json);
-  VLOG(1) << json;
+  base::JSONWriter::Write(value.get(), false, &json);
+  if (!file_.get()) {
+    VLOG(1) << json;
+  } else {
+    fprintf(file_.get(), "%s\n", json.c_str());
+  }
 }
 
diff --git a/chrome/browser/net/net_log_logger.h b/chrome/browser/net/net_log_logger.h
index 564f232..2cb88c6 100644
--- a/chrome/browser/net/net_log_logger.h
+++ b/chrome/browser/net/net_log_logger.h
@@ -6,14 +6,23 @@
 #define CHROME_BROWSER_NET_NET_LOG_LOGGER_H_
 #pragma once
 
+#include "base/scoped_handle.h"
 #include "chrome/browser/net/chrome_net_log.h"
 
+class FilePath;
+
 // NetLogLogger watches the NetLog event stream, and sends all entries to
-// VLOG(1).  This is to debug errors that prevent getting to the
-// about:net-internals page.
+// VLOG(1) or a path specified on creation.  This is to debug errors that
+// prevent getting to the about:net-internals page.
+//
+// Relies on ChromeNetLog only calling an Observer once at a time for
+// thread-safety.
 class NetLogLogger : public ChromeNetLog::ThreadSafeObserver {
  public:
-  NetLogLogger();
+  // If |log_path| is empty or file creation fails, writes to VLOG(1).
+  // Otherwise, writes to |log_path|.  Uses one line per entry, for
+  // easy parsing.
+  explicit NetLogLogger(const FilePath &log_path);
   ~NetLogLogger();
 
   // ThreadSafeObserver implementation:
@@ -24,6 +33,8 @@ class NetLogLogger : public ChromeNetLog::ThreadSafeObserver {
                           net::NetLog::EventParameters* params);
 
  private:
+  ScopedStdioHandle file_;
+
   DISALLOW_COPY_AND_ASSIGN(NetLogLogger);
 };
 
diff --git a/chrome/browser/resources/net_internals/dataview.js b/chrome/browser/resources/net_internals/dataview.js
index 2535303..5db47ff 100644
--- a/chrome/browser/resources/net_internals/dataview.js
+++ b/chrome/browser/resources/net_internals/dataview.js
@@ -19,7 +19,12 @@ function DataView(mainBoxId,
                   byteLoggingCheckboxId,
                   passivelyCapturedCountId,
                   activelyCapturedCountId,
-                  deleteAllId) {
+                  deleteAllId,
+                  dumpDataDivId,
+                  loadDataDivId,
+                  loadLogFileId,
+                  capturingTextSpanId,
+                  loggingTextSpanId) {
   DivView.call(this, mainBoxId);
 
   this.textPre_ = document.getElementById(outputTextBoxId);
@@ -40,6 +45,14 @@ function DataView(mainBoxId,
   document.getElementById(deleteAllId).onclick =
       g_browser.deleteAllEvents.bind(g_browser);
 
+  this.dumpDataDiv_ = document.getElementById(dumpDataDivId);
+  this.loadDataDiv_ = document.getElementById(loadDataDivId);
+  this.capturingTextSpan_ = document.getElementById(capturingTextSpanId);
+  this.loggingTextSpan_ = document.getElementById(loggingTextSpanId);
+
+  document.getElementById(loadLogFileId).onclick =
+      g_browser.loadLogFile.bind(g_browser);
+
   this.updateEventCounts_();
   this.waitingForUpdate_ = false;
 
@@ -71,6 +84,18 @@ DataView.prototype.onAllLogEntriesDeleted = function() {
 };
 
 /**
+ * Called when either a log file is loaded or when going back to actively
+ * logging events.  In either case, called after clearing the old entries,
+ * but before getting any new ones.
+ */
+DataView.prototype.onSetIsViewingLogFile = function(isViewingLogFile) {
+  setNodeDisplay(this.dumpDataDiv_, !isViewingLogFile);
+  setNodeDisplay(this.capturingTextSpan_, !isViewingLogFile);
+  setNodeDisplay(this.loggingTextSpan_, isViewingLogFile);
+  this.setText_('');
+};
+
+/**
  * Updates the counters showing how many events have been captured.
  */
 DataView.prototype.updateEventCounts_ = function() {
@@ -108,6 +133,10 @@ DataView.prototype.onExportToText_ = function() {
  * Presents the captured data as formatted text.
  */
 DataView.prototype.onUpdateAllCompleted = function(data) {
+  // It's possible for a log file to be loaded while a dump is being generated.
+  // When that happens, don't display the log dump, to avoid any confusion.
+  if (g_browser.isViewingLogFile())
+    return;
   this.waitingForUpdate_ = false;
   var text = [];
 
diff --git a/chrome/browser/resources/net_internals/eventsview.js b/chrome/browser/resources/net_internals/eventsview.js
index 7af86aa..d3768ed 100644
--- a/chrome/browser/resources/net_internals/eventsview.js
+++ b/chrome/browser/resources/net_internals/eventsview.js
@@ -475,10 +475,20 @@ EventsView.prototype.onLogEntriesDeleted = function(sourceIds) {
 /**
  * Called whenever all log events are deleted.
  */
-EventsView.prototype.onAllLogEntriesDeleted = function(offset) {
+EventsView.prototype.onAllLogEntriesDeleted = function() {
   this.initializeSourceList_();
 };
 
+/**
+ * Called when either a log file is loaded or when going back to actively
+ * logging events.  In either case, called after clearing the old entries,
+ * but before getting any new ones.
+ */
+EventsView.prototype.onSetIsViewingLogFile = function(isViewingLogFile) {
+  // Needed to sort new sourceless entries correctly.
+  this.maxReceivedSourceId_ = 0;
+};
+
 EventsView.prototype.incrementPrefilterCount = function(offset) {
   this.numPrefilter_ += offset;
   this.invalidateFilterCounter_();
diff --git a/chrome/browser/resources/net_internals/index.html b/chrome/browser/resources/net_internals/index.html
index 732c4be..0cbadb7 100644
--- a/chrome/browser/resources/net_internals/index.html
+++ b/chrome/browser/resources/net_internals/index.html
@@ -202,23 +202,41 @@ found in the LICENSE file.
     <table width=100%>
     <tr>
     <td valign=top>
-      <h2>Dump data</h2>
-      <div style="margin: 8px">
-        <p><input id=securityStrippingCheckbox type=checkbox checked=yes>
-           Strip private information (cookies and credentials).
-        </p>
-        <p>
-          <a href="javascript:displayHelpForBugDump()">
-            Help: How to get data for bug reports?
-          </a>
-        </p>
-        <button id=exportToText class=bigButton>Dump to text</button>
+      <div id=dataViewDumpDataDiv>
+        <h2>Dump data</h2>
+        <div style="margin: 8px">
+          <p><input id=securityStrippingCheckbox type=checkbox checked=yes>
+             Strip private information (cookies and credentials).
+          </p>
+          <p>
+            <a href="javascript:displayHelpForBugDump()">
+              Help: How to get data for bug reports?
+            </a>
+          </p>
+          <button id=exportToText class=bigButton>Dump to text</button>
+        </div>
+      </div>
+      <div id=dataViewLoadDataDiv>
+        <h2>Load data</h2>
+        <div style="margin: 8px">
+          <p><input type=button value="Load log from file" id=dataViewLoadLogFile /></p>
+          <p>Only works with log files created with "--log-net-log=file_name".</p>
+          <p>Once a log is loaded, this page will stop collecting data, and will
+             only start gathering data again when the page is
+             <a href="javascript:history.go(0);">reloaded</a>.<BR>
+          </p>
+        </div>
       </div>
     </td>
 
     <td align=right valign=top>
-      <div class="capturingBox">
-        <b>Capturing all events...</b>
+      <div class="capturingBox" id=dataViewCapturingBox>
+        <span id=dataViewCapturingTextSpan>
+          <b>Capturing all events...</b>
+        </span>
+        <span id=dataViewLoggingTextSpan style="display: none;">
+          <b>Viewing loaded log file.</b>
+        </span>
         <table style="margin: 8px">
           <tr>
             <td>Passively captured:</td>
diff --git a/chrome/browser/resources/net_internals/main.js b/chrome/browser/resources/net_internals/main.js
index d879c87..de8b43c 100644
--- a/chrome/browser/resources/net_internals/main.js
+++ b/chrome/browser/resources/net_internals/main.js
@@ -75,10 +75,12 @@ function onLoaded() {
   // captured data.
   var dataView = new DataView('dataTabContent', 'exportedDataText',
                               'exportToText', 'securityStrippingCheckbox',
-                              'byteLoggingCheckbox',
-                              'passivelyCapturedCount',
-                              'activelyCapturedCount',
-                              'dataViewDeleteAll');
+                              'byteLoggingCheckbox', 'passivelyCapturedCount',
+                              'activelyCapturedCount', 'dataViewDeleteAll',
+                              'dataViewDumpDataDiv', 'dataViewLoadDataDiv',
+                              'dataViewLoadLogFile',
+                              'dataViewCapturingTextSpan',
+                              'dataViewLoggingTextSpan');
 
   // Create a view which will display the results and controls for connection
   // tests.
@@ -108,6 +110,7 @@ function onLoaded() {
 
   // Create a view which lets you tab between the different sub-views.
   var categoryTabSwitcher = new TabSwitcherView('categoryTabHandles');
+  g_browser.setTabSwitcher(categoryTabSwitcher);
 
   // Populate the main tabs.
   categoryTabSwitcher.addTab('eventsTab', eventsView, false);
@@ -144,6 +147,9 @@ function onLoaded() {
   // Select the initial view based on the current URL.
   window.onhashchange();
 
+  // Inform observers a log file is not currently being displayed.
+  g_browser.setIsViewingLogFile_(false);
+
   // Tell the browser that we are ready to start receiving log events.
   g_browser.sendReady();
 }
@@ -191,6 +197,11 @@ function BrowserBridge() {
   // Next unique id to be assigned to a log entry without a source.
   // Needed to simplify deletion, identify associated GUI elements, etc.
   this.nextSourcelessEventId_ = -1;
+
+  // True when viewing a log file rather than actively logged events.
+  // When viewing a log file, all tabs are hidden except the event view,
+  // and all received events are ignored.
+  this.isViewingLogFile_ = false;
 }
 
 /*
@@ -302,23 +313,19 @@ BrowserBridge.prototype.setLogLevel = function(logLevel) {
   chrome.send('setLogLevel', ['' + logLevel]);
 }
 
+BrowserBridge.prototype.loadLogFile = function() {
+  chrome.send('loadLogFile');
+}
+
 //------------------------------------------------------------------------------
 // Messages received from the browser
 //------------------------------------------------------------------------------
 
 BrowserBridge.prototype.receivedLogEntries = function(logEntries) {
-  for (var e = 0; e < logEntries.length; ++e) {
-    var logEntry = logEntries[e];
-
-    // Assign unique ID, if needed.
-    if (logEntry.source.id == 0) {
-      logEntry.source.id = this.nextSourcelessEventId_;
-      --this.nextSourcelessEventId_;
-    }
-    this.capturedEvents_.push(logEntry);
-    for (var i = 0; i < this.logObservers_.length; ++i)
-      this.logObservers_[i].onLogEntryAdded(logEntry);
-  }
+  // Does nothing if viewing a log file.
+  if (this.isViewingLogFile_)
+    return;
+  this.addLogEntries(logEntries);
 };
 
 BrowserBridge.prototype.receivedLogEventTypeConstants = function(constantsMap) {
@@ -439,9 +446,91 @@ BrowserBridge.prototype.receivedHttpCacheInfo = function(info) {
   this.pollableDataHelpers_.httpCacheInfo.update(info);
 };
 
+BrowserBridge.prototype.loadedLogFile = function(logFileContents) {
+  var match;
+  // Replace carriage returns with linebreaks and then split around linebreaks.
+  var lines = logFileContents.replace(/\r/g, '\n').split('\n');
+  var entries = [];
+  var numInvalidLines = 0;
+
+  for (var i = 0; i < lines.length; ++i) {
+    if (lines[i].trim().length == 0)
+      continue;
+    // Parse all valid lines, skipping any others.
+    try {
+      var entry = JSON.parse(lines[i]);
+      if (entry &&
+          typeof(entry) == 'object' &&
+          entry.phase != undefined &&
+          entry.source != undefined &&
+          entry.time != undefined &&
+          entry.type != undefined) {
+        entries.push(entry);
+        continue;
+      }
+    } catch (err) {
+    }
+    ++numInvalidLines;
+    console.log('Unable to parse log line: ' + lines[i]);
+  }
+
+  if (entries.length == 0) {
+    window.alert('Loading log file failed.');
+    return;
+  }
+
+  this.deleteAllEvents();
+
+  this.setIsViewingLogFile_(true);
+
+  var validEntries = [];
+  for (var i = 0; i < entries.length; ++i) {
+    entries[i].wasPassivelyCaptured = true;
+    if (LogEventType[entries[i].type] != undefined &&
+        LogSourceType[entries[i].source.type] != undefined &&
+        LogEventPhase[entries[i].phase] != undefined) {
+      entries[i].type = LogEventType[entries[i].type];
+      entries[i].source.type = LogSourceType[entries[i].source.type];
+      entries[i].phase = LogEventPhase[entries[i].phase];
+      validEntries.push(entries[i]);
+    } else {
+      // TODO(mmenke):  Do something reasonable when the event type isn't
+      //                found, which could happen when event types are
+      //                removed or added between versions.  Could also happen
+      //                with source types, but less likely.
+      console.log(
+        'Unrecognized values in log entry: ' + JSON.stringify(entry));
+    }
+  }
+
+  this.numPassivelyCapturedEvents_ = validEntries.length;
+  this.addLogEntries(validEntries);
+
+  var numInvalidEntries = entries.length - validEntries.length;
+  if (numInvalidEntries > 0 || numInvalidLines > 0) {
+    window.alert(
+      numInvalidLines.toString() +
+      ' could not be parsed as JSON strings, and ' +
+      numInvalidEntries.toString() +
+      ' entries don\'t have valid data.\n\n' +
+      'Unparseable lines may indicate log file corruption.\n' +
+      'Entries with invalid data may be caused by version differences.\n\n' +
+      'See console for more information.');
+  }
+}
+
 //------------------------------------------------------------------------------
 
 /**
+ * Sets the |categoryTabSwitcher_| of BrowserBridge.  Since views depend on
+ * g_browser being initialized, have to have a BrowserBridge prior to tab
+ * construction.
+ */
+BrowserBridge.prototype.setTabSwitcher = function(categoryTabSwitcher) {
+  this.categoryTabSwitcher_ = categoryTabSwitcher;
+};
+
+/**
  * Adds a listener of log entries. |observer| will be called back when new log
  * data arrives, through:
  *
@@ -592,6 +681,25 @@ BrowserBridge.prototype.getNumPassivelyCapturedEvents = function() {
 };
 
 /**
+ * Sends each entry to all log observers, and updates |capturedEvents_|.
+ * Also assigns unique ids to log entries without a source.
+ */
+BrowserBridge.prototype.addLogEntries = function(logEntries) {
+  for (var e = 0; e < logEntries.length; ++e) {
+    var logEntry = logEntries[e];
+
+    // Assign unique ID, if needed.
+    if (logEntry.source.id == 0) {
+      logEntry.source.id = this.nextSourcelessEventId_;
+      --this.nextSourcelessEventId_;
+    }
+    this.capturedEvents_.push(logEntry);
+    for (var i = 0; i < this.logObservers_.length; ++i)
+      this.logObservers_[i].onLogEntryAdded(logEntry);
+  }
+};
+
+/**
  * Deletes captured events with source IDs in |sourceIds|.
  */
 BrowserBridge.prototype.deleteEventsBySourceId = function(sourceIds) {
@@ -626,6 +734,39 @@ BrowserBridge.prototype.deleteAllEvents = function() {
 };
 
 /**
+ * Informs log observers whether or not future events will be from a log file.
+ * Hides all tabs except the events and data tabs when viewing a log file, shows
+ * them all otherwise.
+ */
+BrowserBridge.prototype.setIsViewingLogFile_ = function(isViewingLogFile) {
+  this.isViewingLogFile_ = isViewingLogFile;
+  var tabIds = this.categoryTabSwitcher_.getAllTabIds();
+
+  for (var i = 0; i < this.logObservers_.length; ++i)
+    this.logObservers_[i].onSetIsViewingLogFile(isViewingLogFile);
+
+  // Shows/hides tabs not used when viewing a log file.
+  for (var i = 0; i < tabIds.length; ++i) {
+    if (tabIds[i] == 'eventsTab' || tabIds[i] == 'dataTab')
+      continue;
+    this.categoryTabSwitcher_.showTabHandleNode(tabIds[i], !isViewingLogFile);
+  }
+
+  if (isViewingLogFile) {
+    var activeTab = this.categoryTabSwitcher_.findActiveTab();
+    if (activeTab.id != 'eventsTab')
+      this.categoryTabSwitcher_.switchToTab('dataTab', null);
+  }
+};
+
+/**
+ * Returns true if a log file is currently being viewed.
+ */
+BrowserBridge.prototype.isViewingLogFile = function() {
+  return this.isViewingLogFile_;
+};
+
+/**
  * If |force| is true, calls all startUpdate functions.  Otherwise, just
  * runs updates with active observers.
  */
diff --git a/chrome/browser/resources/net_internals/proxyview.js b/chrome/browser/resources/net_internals/proxyview.js
index 0f7f68b..a6ff9a9 100644
--- a/chrome/browser/resources/net_internals/proxyview.js
+++ b/chrome/browser/resources/net_internals/proxyview.js
@@ -114,3 +114,7 @@ ProxyView.prototype.onLogEntriesDeleted = function(sourceIds) {
 ProxyView.prototype.onAllLogEntriesDeleted = function() {
   this.clearLog_();
 };
+
+ProxyView.prototype.onSetIsViewingLogFile = function(isViewingLogFile) {
+};
+
diff --git a/chrome/browser/resources/net_internals/tabswitcherview.js b/chrome/browser/resources/net_internals/tabswitcherview.js
index 646c983..18cfa7a 100644
--- a/chrome/browser/resources/net_internals/tabswitcherview.js
+++ b/chrome/browser/resources/net_internals/tabswitcherview.js
@@ -136,6 +136,13 @@ TabSwitcherView.prototype.getAllTabIds = function() {
   return ids;
 };
 
+// Shows/hides the DOM node that is used to select the tab.  Will not change
+// the active tab.
+TabSwitcherView.prototype.showTabHandleNode = function(id, isVisible) {
+  var tab = this.findTabById(id);
+  setNodeDisplay(tab.getTabHandleNode(), isVisible);
+};
+
 //-----------------------------------------------------------------------------
 
 /**