Taking screenshots while running a test

chrome/browser/chromeos/login/screenshot_tester.cc

+// Copyright 2014 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 "chrome/browser/chromeos/login/screenshot_tester.h"
+
+#include "ash/shell.h"
+#include "base/base_export.h"
+#include "base/bind_internal.h"
+#include "base/command_line.h"
+#include "base/memory/weak_ptr.h"
+#include "base/prefs/pref_service.h"
+#include "base/run_loop.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/common/pref_names.h"
+#include "chromeos/chromeos_switches.h"
+#include "content/public/browser/browser_thread.h"
+#include "ui/compositor/compositor_switches.h"
+#include "ui/gfx/image/image.h"
+#include "ui/snapshot/snapshot.h"
+
+namespace chromeos {
+
+ScreenshotTester::ScreenshotTester() : weak_factory_(this) {
+}
+
+ScreenshotTester::~ScreenshotTester() {
+}
+
+bool ScreenshotTester::TryInitialize() {
+  CommandLine& command_line = *CommandLine::ForCurrentProcess();
+  if (!command_line.HasSwitch(switches::kEnableScreenshotTesting))
+    return false;
+  if (!command_line.HasSwitch(::switches::kEnablePixelOutputInTests) ||
+      !command_line.HasSwitch(::switches::kUIEnableImplSidePainting)) {
+    // TODO(elizavetai): make turning on --enable-pixel-output-in-tests
+    // and --ui-enable-impl-side-painting automatical.
+    LOG(ERROR) << "--enable-pixel-output-in-tests and "
+               << "--ui-enable-impl-side-painting are required to take "
+               << "screenshots";
+    return false;
+  }
+  if (!command_line.HasSwitch(switches::kScreenshotDestinationDir)) {
+    LOG(ERROR) << "No destination for screenshots specified";
+    return false;
+  }
+  screenshot_dest_ = command_line.GetSwitchValuePath(
+      chromeos::switches::kScreenshotDestinationDir);
+  return true;
+}
+
+void ScreenshotTester::Run(const std::string& file_name) {
+  TakeScreenshot();
+  PNGFile current_screenshot = screenshot_;
+  UpdateGoldenScreenshot(file_name, current_screenshot);
+}
+
+void ScreenshotTester::UpdateGoldenScreenshot(const std::string& file_name,
+                                              PNGFile png_data) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  if (!png_data) {
+    LOG(ERROR) << "Can't take a screenshot";
+    return;
+  }
+  base::FilePath golden_screenshot_path =
+      screenshot_dest_.AppendASCII(file_name + ".png");
+  if (!base::CreateDirectory(golden_screenshot_path.DirName())) {
+    LOG(ERROR) << "Can't create a directory ";
+    return;
+  }
+  if (static_cast<size_t>(
+          base::WriteFile(golden_screenshot_path,
+                          reinterpret_cast<char*>(&(png_data->data()[0])),
+                          png_data->size())) != png_data->size()) {
+    LOG(ERROR) << "Can't save screenshot";
+  }
+  VLOG(0) << "Golden screenshot updated successfully";
+}
+
+void ScreenshotTester::ReturnScreenshot(PNGFile png_data) {
+  // TODO(elizavetai): rewrite this function so that TakeScreenshot
+  // could return a |PNGFile| -- current screenshot.
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  screenshot_ = png_data;
+  content::BrowserThread::PostTask(
+      content::BrowserThread::UI, FROM_HERE, run_loop_quitter_);
+}
+
+void ScreenshotTester::TakeScreenshot() {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));

[ygorshenin1, 2014/07/21 16:38:43]

nit: it's possible to simplify the check:
DCHECK_CURRENTLY_ON(content::BrowserThread::UI).

[Lisa Ignatyeva, 2014/07/21 16:52:39]

Done.

+  aura::Window* primary_window = ash::Shell::GetPrimaryRootWindow();
+  gfx::Rect rect = primary_window->bounds();
+  ui::GrabWindowSnapshotAsync(primary_window,
+                              rect,
+                              content::BrowserThread::GetBlockingPool(),
+                              base::Bind(&ScreenshotTester::ReturnScreenshot,
+                                         weak_factory_.GetWeakPtr()));
+  base::RunLoop run_loop;
+  run_loop_quitter_ = run_loop.QuitClosure();
+  run_loop.Run();
+}
+
+}  // namespace chromeos