Clean up thread handling in Blimp browser tests.

blimp/engine/browser_tests/blimp_browser_test.h

Index: blimp/engine/browser_tests/blimp_browser_test.h
diff --git a/blimp/engine/browser_tests/blimp_browser_test.h b/blimp/engine/browser_tests/blimp_browser_test.h
index 820ec27e9fbd7fa285924664af12d0d1818812fd..992efb0da054cfde718518f28dce4a0baa80b8f6 100644
--- a/blimp/engine/browser_tests/blimp_browser_test.h
+++ b/blimp/engine/browser_tests/blimp_browser_test.h
@@ -7,6 +7,7 @@
 
 #include <memory>
 
+#include "base/synchronization/waitable_event.h"
 #include "content/public/test/browser_test_base.h"
 
 namespace base {
@@ -33,13 +34,17 @@ class BlimpBrowserTest : public content::BrowserTestBase {
   // exit.
   void QuitRunLoop();
 
+  // Tells RunUntilCompletion() to break and discontinue processing UI & IO
+  // thread MessageLoops.
+  void SignalCompletion();
+
  protected:
   BlimpBrowserTest();
   ~BlimpBrowserTest() override;
 
-  // Run an asynchronous test in a nested run loop. The caller should call
-  // QuitRunLoop() to notify that the test should finish.
-  void RunUntilQuit();
+  // Processes tasks in the UI and IO thread until SignalCompletion() is
+  // called.
+  void RunUntilCompletion();
 
   engine::BlimpEngineSession* GetEngineSession();
 
@@ -50,15 +55,20 @@ class BlimpBrowserTest : public content::BrowserTestBase {
 
   // content::BrowserTestBase implementation.
   void RunTestOnMainThreadLoop() override;
+  void SetUpCommandLine(base::CommandLine* command_line) override;
   void SetUpOnMainThread() override;
   void TearDownOnMainThread() override;
-  void SetUpCommandLine(base::CommandLine* command_line) override;
 
  private:
-  void OnGetEnginePort(uint16_t port);
+  // Receives the port number from an asynchronously connected socket.
+  // Calls SignalCompletion() when set.

[Wez, 2016/08/20 00:40:24]

nit: I suggest being more explicit - this is used during synchronous test setup
to receive the port number from the async socket API, and signal that we're
ready to continue.

Would it help to call this OnGetEnginePortCompletion() to emphasize that it's
not a general-purpose setter?

[Kevin M, 2016/08/22 19:46:56]

Done.

+  void SetEnginePort(uint16_t port);
 
   uint16_t engine_port_;
-  std::unique_ptr<base::RunLoop> run_loop_;
+
+  // Used to signal the completion of asynchronous processing to
+  // RunUntilCompletion().
+  base::WaitableEvent completion_event_;
 
   DISALLOW_COPY_AND_ASSIGN(BlimpBrowserTest);
 };