4 files changed, 52 insertions, 3 deletions
diff --git a/content/browser/tracing/tracing_controller_impl.cc b/content/browser/tracing/tracing_controller_impl.cc
index 8bca4a0..185eb98 100644
--- a/content/browser/tracing/tracing_controller_impl.cc
+++ b/content/browser/tracing/tracing_controller_impl.cc
@@ -10,6 +10,7 @@
 #include "base/json/string_escape.h"
 #include "base/strings/string_number_conversions.h"
 #include "content/browser/tracing/trace_message_filter.h"
+#include "content/browser/tracing/tracing_ui.h"
 #include "content/common/child_process_messages.h"
 #include "content/public/browser/browser_message_filter.h"
 #include "content/public/common/content_switches.h"
@@ -291,7 +292,7 @@ bool TracingControllerImpl::EnableMonitoring(
 
   if (!can_enable_monitoring())
     return false;
-  is_monitoring_ = true;
+  OnMonitoringStateChanged(true);
 
 #if defined(OS_ANDROID)
   TraceLog::GetInstance()->AddClockSyncMetadataEvent();
@@ -353,7 +354,7 @@ void TracingControllerImpl::OnDisableMonitoringDone(
     const DisableMonitoringDoneCallback& callback) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
-  is_monitoring_ = false;
+  OnMonitoringStateChanged(false);
 
   // Notify all child processes.
   for (TraceMessageFilterSet::iterator it = trace_message_filters_.begin();
@@ -782,4 +783,32 @@ void TracingControllerImpl::OnWatchEventMatched() {
     watch_event_callback_.Run();
 }
 
+void TracingControllerImpl::RegisterTracingUI(TracingUI* tracing_ui)
+{
+  DCHECK(tracing_uis_.find(tracing_ui) == tracing_uis_.end());
+  tracing_uis_.insert(tracing_ui);
+  tracing_ui->OnMonitoringStateChanged(is_monitoring_);
+}
+
+void TracingControllerImpl::UnregisterTracingUI(TracingUI* tracing_ui)
+{
+  std::set<TracingUI*>::iterator it = tracing_uis_.find(tracing_ui);
+  DCHECK(it != tracing_uis_.end());
+  tracing_uis_.erase(it);
+}
+
+void TracingControllerImpl::OnMonitoringStateChanged(bool is_monitoring)
+{
+  if (is_monitoring_ == is_monitoring)
+    return;
+
+  is_monitoring_ = is_monitoring;
+#if !defined(OS_ANDROID)
+  for (std::set<TracingUI*>::iterator it = tracing_uis_.begin();
+       it != tracing_uis_.end(); it++) {
+    (*it)->OnMonitoringStateChanged(is_monitoring);
+  }
+#endif
+}
+
 }  // namespace content
diff --git a/content/browser/tracing/tracing_controller_impl.h b/content/browser/tracing/tracing_controller_impl.h
index 0684373..da6039d 100644
--- a/content/browser/tracing/tracing_controller_impl.h
+++ b/content/browser/tracing/tracing_controller_impl.h
@@ -20,6 +20,7 @@ class RefCountedString;
 namespace content {
 
 class TraceMessageFilter;
+class TracingUI;
 
 class TracingControllerImpl : public TracingController {
  public:
@@ -54,6 +55,9 @@ class TracingControllerImpl : public TracingController {
                              const WatchEventCallback& callback) OVERRIDE;
   virtual bool CancelWatchEvent() OVERRIDE;
 
+  void RegisterTracingUI(TracingUI* tracing_ui);
+  void UnregisterTracingUI(TracingUI* tracing_ui);
+
  private:
   typedef std::set<scoped_refptr<TraceMessageFilter> > TraceMessageFilterSet;
   class ResultFile;
@@ -136,6 +140,8 @@ class TracingControllerImpl : public TracingController {
                               const EnableMonitoringDoneCallback& callback);
   void OnDisableMonitoringDone(const DisableMonitoringDoneCallback& callback);
 
+  void OnMonitoringStateChanged(bool is_monitoring);
+
   TraceMessageFilterSet trace_message_filters_;
 
   // Pending acks for DisableRecording.
@@ -162,6 +168,7 @@ class TracingControllerImpl : public TracingController {
   WatchEventCallback watch_event_callback_;
 
   std::set<std::string> known_category_groups_;
+  std::set<TracingUI*> tracing_uis_;
   scoped_ptr<ResultFile> result_file_;
   scoped_ptr<ResultFile> monitoring_snapshot_file_;
   DISALLOW_COPY_AND_ASSIGN(TracingControllerImpl);
diff --git a/content/browser/tracing/tracing_ui.cc b/content/browser/tracing/tracing_ui.cc
index 6b541f8..2f71e71 100644
--- a/content/browser/tracing/tracing_ui.cc
+++ b/content/browser/tracing/tracing_ui.cc
@@ -16,6 +16,7 @@
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/values.h"
+#include "content/browser/tracing/tracing_controller_impl.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/tracing_controller.h"
 #include "content/public/browser/web_contents.h"
@@ -243,6 +244,16 @@ TracingUI::TracingUI(WebUI* web_ui) : WebUIController(web_ui) {
   source->AddResourcePath("tracing.js", IDR_TRACING_JS);
   source->SetRequestFilter(base::Bind(OnTracingRequest));
   WebUIDataSource::Add(browser_context, source);
+  TracingControllerImpl::GetInstance()->RegisterTracingUI(this);
+}
+
+TracingUI::~TracingUI() {
+  TracingControllerImpl::GetInstance()->UnregisterTracingUI(this);
+}
+
+void TracingUI::OnMonitoringStateChanged(bool is_monitoring) {
+  web_ui()->CallJavascriptFunction(
+      "onMonitoringStateChanged", base::FundamentalValue(is_monitoring));
 }
 
 }  // namespace content
diff --git a/content/browser/tracing/tracing_ui.h b/content/browser/tracing/tracing_ui.h
index 85bbce1..40ce082 100644
--- a/content/browser/tracing/tracing_ui.h
+++ b/content/browser/tracing/tracing_ui.h
@@ -10,9 +10,11 @@
 namespace content {
 
 // The C++ back-end for the chrome://tracing webui page.
-class TracingUI : public WebUIController {
+class CONTENT_EXPORT TracingUI : public WebUIController {
  public:
   explicit TracingUI(WebUI* web_ui);
+  virtual ~TracingUI();
+  void OnMonitoringStateChanged(bool is_monitoring);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TracingUI);