implement SetWatchEvent and WaitForEvent for trace-based-tests

chrome/test/base/tracing.cc

Index: chrome/test/base/tracing.cc
diff --git a/chrome/test/base/tracing.cc b/chrome/test/base/tracing.cc
index 7e609ec6d515255ed68ae2b7bb40ac5343b3393b..9ab978d35a32318ae439c1dd41164a09abafc1b4 100644
--- a/chrome/test/base/tracing.cc
+++ b/chrome/test/base/tracing.cc
@@ -7,27 +7,64 @@
 #include "base/debug/trace_event.h"
 #include "base/memory/singleton.h"
 #include "base/message_loop.h"
+#include "content/public/browser/browser_thread.h"
 #include "content/public/browser/trace_controller.h"
 #include "content/public/browser/trace_subscriber.h"
 #include "content/public/test/test_utils.h"
 
 namespace {
 
+using content::BrowserThread;
+
 class InProcessTraceController : public content::TraceSubscriber {
  public:
   static InProcessTraceController* GetInstance() {
     return Singleton<InProcessTraceController>::get();
   }
 
-  InProcessTraceController() {}
+  InProcessTraceController()
+      : is_waiting_on_watch_(false),
+        watch_notification_count_(0) {}
   virtual ~InProcessTraceController() {}
 
   bool BeginTracing(const std::string& categories) {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
     return content::TraceController::GetInstance()->BeginTracing(
         this, categories);
   }
 
+  bool BeginTracingWithWatch(const std::string& categories,
+                             const std::string& category_name,
+                             const std::string& event_name,
+                             int num_occurrences) {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+    DCHECK(num_occurrences > 0);
+    watch_notification_count_ = num_occurrences;
+    return BeginTracing(categories) &&
+           content::TraceController::GetInstance()->SetWatchEvent(
+               this, category_name, event_name);
+  }
+
+  bool WaitForWatchEvent(base::TimeDelta timeout) {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+    if (watch_notification_count_ == 0)
+      return true;
+
+    if (timeout != base::TimeDelta()) {
+      timer_.Start(FROM_HERE, timeout, this,
+                   &InProcessTraceController::Timeout);
+    }
+
+    is_waiting_on_watch_ = true;
+    message_loop_runner_ = new content::MessageLoopRunner;
+    message_loop_runner_->Run();
+    is_waiting_on_watch_ = false;
+
+    return watch_notification_count_ == 0;
+  }
+
   bool EndTracing(std::string* json_trace_output) {
+    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
     using namespace base::debug;
 
     TraceResultBuffer::SimpleOutput output;
@@ -44,28 +81,53 @@ class InProcessTraceController : public content::TraceSubscriber {
     trace_buffer_.SetOutputCallback(TraceResultBuffer::OutputCallback());
 
     *json_trace_output = output.json_output;
+
+    // Watch notifications can occur during this method's message loop run, but
+    // not after, so clear them here.
+    watch_notification_count_ = 0;
     return true;
   }
 
  private:
   friend struct DefaultSingletonTraits<InProcessTraceController>;
 
-  // TraceSubscriber
+  // TraceSubscriber implementation
   virtual void OnEndTracingComplete() OVERRIDE {
     message_loop_runner_->Quit();
   }
 
-  // TraceSubscriber
+  // TraceSubscriber implementation
   virtual void OnTraceDataCollected(
       const scoped_refptr<base::RefCountedString>& trace_fragment) OVERRIDE {
     trace_buffer_.AddFragment(trace_fragment->data());
   }
 
+  // TraceSubscriber implementation
+  virtual void OnEventWatchNotification() OVERRIDE {
+    if (watch_notification_count_ == 0)
+      return;
+    if (--watch_notification_count_ == 0) {
+      timer_.Stop();
+      if (is_waiting_on_watch_)
+        message_loop_runner_->Quit();
+    }
+  }
+
+  void Timeout() {
+    DCHECK(is_waiting_on_watch_);
+    message_loop_runner_->Quit();
+  }
+
   // For collecting trace data asynchronously.
   base::debug::TraceResultBuffer trace_buffer_;
 
   scoped_refptr<content::MessageLoopRunner> message_loop_runner_;
 
+  base::OneShotTimer<InProcessTraceController> timer_;
+
+  bool is_waiting_on_watch_;
+  int watch_notification_count_;
+
   DISALLOW_COPY_AND_ASSIGN(InProcessTraceController);
 };
 
@@ -77,6 +139,18 @@ bool BeginTracing(const std::string& categories) {
   return InProcessTraceController::GetInstance()->BeginTracing(categories);
 }
 
+bool BeginTracingWithWatch(const std::string& categories,
+                           const std::string& category_name,
+                           const std::string& event_name,
+                           int num_occurrences) {
+  return InProcessTraceController::GetInstance()->BeginTracingWithWatch(
+      categories, category_name, event_name, num_occurrences);
+}
+
+bool WaitForWatchEvent(base::TimeDelta timeout) {
+  return InProcessTraceController::GetInstance()->WaitForWatchEvent(timeout);
+}
+
 bool EndTracing(std::string* json_trace_output) {
   return InProcessTraceController::GetInstance()->EndTracing(json_trace_output);
 }