Add a few CHECK()s to troubleshoot crbug.com/1342152

This adds a few CHECK()s to enforce the assume invariants while
destroying browser contexts during headless shutdown.

Bug: 1342152
Change-Id: I496f1cb231bbe892e537afe694f73e45ad089536
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3827419
Reviewed-by: Peter Kvitek <kvitekp@chromium.org>
Commit-Queue: Peter Kvitek <kvitekp@chromium.org>
Auto-Submit: Andrey Kosyakov <caseq@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1034985}

headless/lib/browser/headless_browser_impl.cc

@@ -53,6 +53,7 @@ HeadlessBrowserImpl::BrowserMainThread() const {
 
 void HeadlessBrowserImpl::Shutdown() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  did_shutdown_ = true;
 
   weak_ptr_factory_.InvalidateWeakPtrs();
   // Make sure GetAllBrowserContexts is sane if called after this point.
@@ -103,15 +104,10 @@ HeadlessBrowserContext* HeadlessBrowserImpl::CreateBrowserContext(
     HeadlessBrowserContext::Builder* builder) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
-  std::unique_ptr<HeadlessBrowserContextImpl> browser_context =
-      HeadlessBrowserContextImpl::Create(builder);
-
-  if (!browser_context) {
-    return nullptr;
-  }
+  CHECK(!did_shutdown_);
 
+  auto browser_context = HeadlessBrowserContextImpl::Create(builder);
   HeadlessBrowserContext* result = browser_context.get();
-
   browser_contexts_[browser_context->Id()] = std::move(browser_context);
 
   return result;

headless/lib/browser/headless_browser_impl.h

@@ -121,6 +121,8 @@ class HEADLESS_EXPORT HeadlessBrowserImpl : public HeadlessBrowser,
   policy::PolicyService* GetPolicyService();
 #endif
 
+  bool did_shutdown() const { return did_shutdown_; }
+
  protected:
 #if BUILDFLAG(IS_MAC)
   std::unique_ptr<display::ScopedNativeScreen> screen_;
@@ -133,7 +135,7 @@ class HEADLESS_EXPORT HeadlessBrowserImpl : public HeadlessBrowser,
   base::flat_map<std::string, std::unique_ptr<HeadlessBrowserContextImpl>>
       browser_contexts_;
   raw_ptr<HeadlessBrowserContext> default_browser_context_;  // Not owned.
-
+  bool did_shutdown_ = false;  // TODO(1342152): remove once the bug is fixed.
   scoped_refptr<content::DevToolsAgentHost> agent_host_;
   std::unique_ptr<HeadlessRequestContextManager>
       system_request_context_manager_;

headless/lib/browser/headless_browser_main_parts.cc

@@ -72,6 +72,10 @@ void HeadlessBrowserMainParts::WillRunMainMessageLoop(
 }
 
 void HeadlessBrowserMainParts::PostMainMessageLoopRun() {
+  // HeadlessBrowserImpl::Shutdown() is supposed to remove all browser contexts
+  // and therefore all associated web contents, however crbug.com/1342152
+  // implies it may not be happening.
+  CHECK_EQ(0U, browser_->GetAllBrowserContexts().size());
   if (devtools_http_handler_started_) {
     StopLocalDevToolsHttpHandler();
     devtools_http_handler_started_ = false;

headless/lib/headless_content_main_delegate.cc

@@ -391,6 +391,7 @@ HeadlessContentMainDelegate::RunProcess(
                              "HeadlessContentMainDelegate::RunProcess";
 
   browser_runner->Run();
+  CHECK(browser_->did_shutdown());
   browser_runner->Shutdown();
   browser_.reset();