Split up leak detector into two stages for better leak reporting.

content/public/test/render_view_test.cc

 // Copyright (c) 2012 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.
 
 #include "content/public/test/render_view_test.h"
 
 #include <cctype>
 
 #include "base/location.h"
 #include "base/run_loop.h"
@@ skipping 275 matching lines @@
 
 void RenderViewTest::TearDown() {
   // Run the loop so the release task from the renderwidget executes.
   ProcessPendingMessages();
 
   render_thread_->SendCloseMessage();
 
   scoped_ptr<blink::WebLeakDetector> leak_detector =
       make_scoped_ptr(blink::WebLeakDetector::create(this));
 
+  leak_detector->delayFinalGarbageCollection();

[haraken, 2015/11/24 23:54:51]

Would you elaborate on why we need to delay the GC?

[sof, 2015/11/25 06:20:50]

Clearing view_ below will trigger a close() on the frame _and_ its frame tree,
which will release (self-)Persistent<>s, allowing objects to be swept at the
next GC.

If we don't ensure/guarantee that any of the leak detector's GCs run after that
close() has gone ahead, we will see frame leaks reported.

[haraken, 2015/11/25 07:39:38]

Doesn't it mean just that we need to trigger another GC after clearing view_?
(i.e., don't need to delay the GC; we can just trigger another GC after clearing
view_.)

I'd prefer not introducing a complicated logic like delaying.

   leak_detector->collectGarbageAndGetDOMCounts(GetMainFrame());
 
   view_ = NULL;
   mock_process_.reset();
 
   // After telling the view to close and resetting mock_process_ we may get
   // some new tasks which need to be processed before shutting down WebKit
   // (http://crbug.com/21508).
   base::RunLoop().RunUntilIdle();
 
 #if defined(OS_MACOSX)
   // Needs to run before blink::shutdown().
   autorelease_pool_.reset(NULL);
 #endif
 
+  leak_detector->collectFinalGarbage();
+
   blink_platform_impl_.Shutdown();
   blink::shutdown();
 
   platform_->PlatformUninitialize();
   platform_.reset();
   params_.reset();
   command_line_.reset();
 }
 
 void RenderViewTest::onLeakDetectionComplete(const Result& result) {
@@ skipping 291 matching lines @@
   TestRenderFrame* frame =
       static_cast<TestRenderFrame*>(impl->GetMainRenderFrame());
   frame->Navigate(common_params, StartNavigationParams(), request_params);
 
   // The load actually happens asynchronously, so we pump messages to process
   // the pending continuation.
   FrameLoadWaiter(frame).Wait();
 }
 
 }  // namespace content