Reland "[filesapp] Add a browser_test for DevToolsListener class"

This is a reland of c67306a2, which was
reverted due to to uninitialized variable MSAN error. That was fixed on
CL:2466572; re-landing the original change c67306a2 therefore.
.
Original change's description:
> [filesapp] Add a browser_test for DevToolsListener class
>
> Test that JS code coverage of a JS IFFE injected in a WebContents gets
> collected by DevToolsListener and stored in a ScopedTempDir.
>
> Test: browser_tests --gtest_filter="*DevToolsListener*"
> Bug: 1113941
> Change-Id: I8f04f2e704d677823ffa154272605798b7046f77
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2461602
> Commit-Queue: Ben Reich <benreich@chromium.org>
> Commit-Queue: Noel Gordon <noel@chromium.org>
> Reviewed-by: Noel Gordon <noel@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#816064}

Bug: 1113941
Change-Id: I491101bbe9a8cf050ddfe39842a3f0bd4fb2ec26
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2467165Reviewed-by: Noel Gordon <noel@chromium.org>
Commit-Queue: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816480}

chrome/browser/chromeos/file_manager/devtools_listener_browsertest.cc

+// Copyright 2020 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 <map>
+
+#include "base/files/file_util.h"
+#include "base/path_service.h"
+#include "base/process/process_handle.h"
+#include "chrome/browser/chromeos/file_manager/devtools_listener.h"
+#include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.h"
+#include "chrome/common/chrome_paths.h"
+#include "chrome/test/base/in_process_browser_test.h"
+#include "chrome/test/base/ui_test_utils.h"
+#include "content/public/browser/devtools_agent_host_observer.h"
+#include "content/public/test/browser_test.h"
+#include "content/public/test/browser_test_utils.h"
+#include "net/test/embedded_test_server/embedded_test_server.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace file_manager {
+
+class DevToolsListenerBrowserTest : public content::DevToolsAgentHostObserver,
+                                    public InProcessBrowserTest {
+ public:
+  DevToolsListenerBrowserTest() = default;
+
+  void SetUpOnMainThread() override {
+    process_id_ = base::GetUniqueIdForProcess().GetUnsafeValue();
+    content::DevToolsAgentHost::AddObserver(this);
+
+    base::ScopedAllowBlockingForTesting allow_blocking;
+    CHECK(tmp_dir_.CreateUniqueTempDir());
+  }
+
+  bool ShouldForceDevToolsAgentHostCreation() override { return true; }
+
+  void DevToolsAgentHostCreated(content::DevToolsAgentHost* host) override {
+    CHECK(devtools_agent_.find(host) == devtools_agent_.end());
+    devtools_agent_[host].reset(new DevToolsListener(host, process_id_));
+  }
+
+  void DevToolsAgentHostAttached(content::DevToolsAgentHost* host) override {}
+
+  void DevToolsAgentHostNavigated(content::DevToolsAgentHost* host) override {
+    if (devtools_agent_.find(host) == devtools_agent_.end())
+      return;
+    devtools_agent_.find(host)->second->Navigated(host);
+  }
+
+  void DevToolsAgentHostDetached(content::DevToolsAgentHost* host) override {}
+
+  void DevToolsAgentHostCrashed(content::DevToolsAgentHost* host,
+                                base::TerminationStatus status) override {
+    if (devtools_agent_.find(host) == devtools_agent_.end())
+      return;
+    NOTREACHED();
+  }
+
+  void CollectCodeCoverage() {
+    base::ScopedAllowBlockingForTesting allow_blocking;
+
+    base::FilePath coverage_store =
+        tmp_dir_.GetPath().AppendASCII("devtools_listener_browser_test");
+    CHECK(base::CreateDirectory(coverage_store));
+
+    for (auto& agent : devtools_agent_) {
+      auto* host = agent.first;
+      EXPECT_TRUE(agent.second->HasCoverage(host));
+      agent.second->GetCoverage(host, coverage_store, "fake_test_name");
+      agent.second->Detach(host);
+    }
+
+    ASSERT_FALSE(base::IsDirectoryEmpty(coverage_store));
+  }
+
+ private:
+  base::ScopedTempDir tmp_dir_;
+  uint32_t process_id_ = 0;
+  std::map<content::DevToolsAgentHost*, std::unique_ptr<DevToolsListener>>
+      devtools_agent_;
+  base::FilePath coverage_store_;
+
+  DISALLOW_COPY_AND_ASSIGN(DevToolsListenerBrowserTest);
+};
+
+IN_PROC_BROWSER_TEST_F(DevToolsListenerBrowserTest, CanCollectCodeCoverage) {
+  base::FilePath test_data_dir;
+  base::PathService::Get(chrome::DIR_TEST_DATA, &test_data_dir);
+  embedded_test_server()->ServeFilesFromDirectory(test_data_dir);
+
+  ASSERT_TRUE(embedded_test_server()->Start());
+  ui_test_utils::NavigateToURLBlockUntilNavigationsComplete(
+      browser(), embedded_test_server()->GetURL("/title2.html"), 1);
+
+  content::WebContents* web_contents =
+      browser()->tab_strip_model()->GetActiveWebContents();
+  ASSERT_TRUE(
+      content::ExecJs(web_contents, "(function() { console.log('test'); })()"));
+
+  content::DevToolsAgentHost::RemoveObserver(this);
+  content::RunAllTasksUntilIdle();
+
+  CollectCodeCoverage();
+
+  content::DevToolsAgentHost::DetachAllClients();
+  content::RunAllTasksUntilIdle();
+}
+
+}  // namespace file_manager

chrome/test/BUILD.gn

@@ -2394,6 +2394,7 @@ if (!is_android) {
         "../browser/chromeos/file_manager/audio_player_browsertest.cc",
         "../browser/chromeos/file_manager/devtools_listener.cc",
         "../browser/chromeos/file_manager/devtools_listener.h",
+        "../browser/chromeos/file_manager/devtools_listener_browsertest.cc",
         "../browser/chromeos/file_manager/external_filesystem_apitest.cc",
         "../browser/chromeos/file_manager/file_manager_base_jstest.cc",
         "../browser/chromeos/file_manager/file_manager_browsertest.cc",