Add a browser test that can communicate with the layout test framework and print pdfs.

chrome/browser/printing/print_preview_pdf_generated_browsertest.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 <algorithm>

[Lei Zhang, 2014/07/17 23:31:06]

I would make a pass through the #includes and remove the ones you are not using.

+#include <cstdio>
+#include <fstream>
+#include <iostream>
+#include <iterator>
+#include <limits>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "base/file_util.h"
+#include "base/files/file.h"
+#include "base/files/file_path.h"
+#include "base/files/scoped_temp_dir.h"
+#include "base/format_macros.h"
+#include "base/logging.h"
+#include "base/md5.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/numerics/safe_conversions.h"
+#include "base/path_service.h"
+#include "base/run_loop.h"
+#include "base/scoped_native_library.h"
+#include "base/strings/string16.h"
+#include "base/strings/string_piece.h"
+#include "base/strings/string_split.h"
+#include "base/strings/string_util.h"
+#include "base/strings/utf_string_conversions.h"
+#include "chrome/app/chrome_command_ids.h"
+#include "chrome/browser/net/referrer.h"
+#include "chrome/browser/printing/print_preview_dialog_controller.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/browser_commands.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.h"
+#include "chrome/browser/ui/webui/print_preview/print_preview_handler.h"
+#include "chrome/browser/ui/webui/print_preview/print_preview_ui.h"
+#include "chrome/browser/ui/webui/print_preview/sticky_settings.h"
+#include "chrome/common/chrome_paths.h"
+#include "chrome/common/print_messages.h"
+#include "chrome/common/url_constants.h"
+#include "chrome/test/base/in_process_browser_test.h"
+#include "chrome/test/base/ui_test_utils.h"
+#include "content/public/browser/web_contents.h"
+#include "content/public/browser/web_ui_message_handler.h"
+#include "content/public/common/page_transition_types.h"
+#include "content/public/test/browser_test_utils.h"
+#include "content/public/test/test_navigation_observer.h"
+#include "content/public/test/test_utils.h"
+#include "ipc/ipc_message_macros.h"
+#include "net/base/filename_util.h"
+#include "printing/pdf_render_settings.h"
+#include "printing/units.h"
+#include "ui/events/keycodes/keyboard_codes.h"
+#include "ui/gfx/codec/png_codec.h"
+#include "ui/gfx/geometry/rect.h"
+#include "url/gurl.h"
+
+#if defined(OS_WIN)
+#include <fcntl.h>
+#include <io.h>
+#endif
+
+using content::WebContents;
+using content::WebContentsObserver;
+
+namespace printing {
+
+// Number of color channels in a BGRA bitmap.
+const int kColorChannels = 4;
+const int kDpi = 300;
+
+// Every state is used when the document is a non-PDF source. When the source is
+// a PDF, kWaitingToSendSaveAsPDF, kWaitingToSendPageNumbers, and
+// kWaitingForFinalMessage are the only states used.
+enum State {
+  // Waiting for the first message so the program can select Save as PDF
+  kWaitingToSendSaveAsPdf = 0,
+  // Waiting for the second message so the test can set the layout
+  kWaitingToSendLayoutSettings = 1,
+  // Waiting for the third message so the test can set the page numbers
+  kWaitingToSendPageNumbers = 2,
+  // Waiting for the forth message so the test can set the headers checkbox
+  kWaitingToSendHeadersAndFooters = 3,
+  // Waiting for the fifth message so the test can set the background checkbox
+  kWaitingToSendBackgroundColorsAndImages = 4,
+  // Waiting for the sixth message so the test can set the margins combobox
+  kWaitingToSendMargins = 5,
+  // Waiting for the final message so the program can save to PDF.
+  kWaitingForFinalMessage = 6,
+};
+
+// Settings for print preview. It reflects the current options provided by
+// print preview. If more options are added, more states should be added and
+// there should be more settings added to this struct.
+struct PrintPreviewSettings {
+  PrintPreviewSettings(bool is_portrait,
+                       std::string page_numbers,
+                       bool headers_and_footers,
+                       bool background_colors_and_images,
+                       MarginType margins,
+                       bool is_already_pdf)

[Lei Zhang, 2014/07/17 23:31:05]

How about we name this |source_is_pdf| ?

[ivandavid, 2014/07/18 01:59:10]

Done.

+      : is_portrait(is_portrait),
+        page_numbers(page_numbers),
+        headers_and_footers(headers_and_footers),
+        background_colors_and_images(background_colors_and_images),
+        margins(margins),
+        is_already_pdf(is_already_pdf) {}
+
+  bool is_portrait;
+  std::string page_numbers;
+  bool headers_and_footers;
+  bool background_colors_and_images;
+  MarginType margins;
+  bool is_already_pdf;
+};
+
+// Observes the print preview webpage. Once it observes the PreviewPageCount
+// message, will send a sequence of commands to the print preview dialog and
+// change the settings of the preview dialog.
+class PrintPreviewObserver : public WebContentsObserver {
+ public:
+  PrintPreviewObserver(Browser* browser, WebContents* dialog)
+      : WebContentsObserver(dialog),
+        browser_(browser),
+        state_(kWaitingToSendSaveAsPdf),
+        failed_setting_("None") {}
+
+  virtual ~PrintPreviewObserver() {}
+
+  // Sets closure for the observer so that it can end the loop.
+  void set_quit_closure(const base::Closure &closure) {
+    quit_closure_ = closure;
+  }
+
+  // Actually stops the message loop so that the test can proceed.
+  void EndLoop() {
+    base::MessageLoop::current()->PostTask(FROM_HERE, quit_closure_);
+  }
+
+  bool OnMessageReceived(const IPC::Message& message) OVERRIDE {
+    IPC_BEGIN_MESSAGE_MAP(PrintPreviewObserver, message)
+      IPC_MESSAGE_HANDLER(PrintHostMsg_DidGetPreviewPageCount,
+                          OnDidGetPreviewPageCount)
+    IPC_END_MESSAGE_MAP();
+    return false;
+  }
+
+  // Gets the web contents for the print preview dialog so that the UI and
+  // other elements can be accessed.
+  WebContents* GetDialog() {
+    WebContents* tab = browser_->tab_strip_model()->GetActiveWebContents();
+    PrintPreviewDialogController* dialog_controller =
+        PrintPreviewDialogController::GetInstance();
+    WebContents* web_contents =

[Lei Zhang, 2014/07/17 23:31:06]

Just drop this variable and return instead.

[ivandavid, 2014/07/18 01:59:11]

Done.

+        dialog_controller->GetPrintPreviewForContents(tab);
+    return web_contents;
+  }
+
+  // Gets the PrintPreviewUI so that certain elements can be accessed.
+  PrintPreviewUI* GetUI() {
+    return static_cast<PrintPreviewUI*>(
+        GetDialog()->GetWebUI()->GetController());
+  }
+
+  // Calls native_layer.onManipulateSettingsForTest() and sends a dictionary
+  // value containing the type of setting and the value to set that settings
+  // to.
+  void ManipulatePreviewSettings() {
+    base::DictionaryValue script_argument;
+
+    if (state_ == kWaitingToSendSaveAsPdf) {
+      script_argument.SetBoolean("selectSaveAsPdfDestination", true);
+      state_ = settings_->is_already_pdf ?
+               kWaitingToSendPageNumbers : kWaitingToSendLayoutSettings;
+      failed_setting_ = "Save as PDF";
+    } else if (state_ == kWaitingToSendLayoutSettings) {
+      script_argument.SetBoolean("layoutSettings.portrait",
+                                 settings_->is_portrait);
+      state_ = kWaitingToSendPageNumbers;
+      failed_setting_ = "Layout Settings";
+    } else if (state_ == kWaitingToSendPageNumbers) {
+      script_argument.SetString("pageRange", settings_->page_numbers);
+      state_ = settings_->is_already_pdf ?
+               kWaitingForFinalMessage : kWaitingToSendHeadersAndFooters;
+      failed_setting_ = "Page Range";
+    } else if (state_ == kWaitingToSendHeadersAndFooters) {
+      script_argument.SetBoolean("headersAndFooters",
+                                 settings_->headers_and_footers);
+      state_ = kWaitingToSendBackgroundColorsAndImages;
+      failed_setting_ = "Headers and Footers";
+    } else if (state_ == kWaitingToSendBackgroundColorsAndImages) {
+      script_argument.SetBoolean("backgroundColorsAndImages",
+                                 settings_->background_colors_and_images);
+      state_ = kWaitingToSendMargins;
+      failed_setting_ = "Background Colors and Images";
+    } else if (state_ == kWaitingToSendMargins) {
+      script_argument.SetInteger("margins", settings_->margins);
+      state_ = kWaitingForFinalMessage;
+      failed_setting_ = "Margins";
+    } else if (state_ == kWaitingForFinalMessage) {
+      EndLoop();
+      return;
+    }
+
+    ASSERT_FALSE(script_argument.empty());
+    GetUI()->web_ui()->CallJavascriptFunction(
+        "onManipulateSettingsForTest", script_argument);
+  }
+
+  // Saves the print preview settings to be sent to the print preview dialog.
+  void SetPrintPreviewSettings(const PrintPreviewSettings& settings) {
+    settings_.reset(new PrintPreviewSettings(settings));
+  }
+
+  // Returns the setting that could not be set in the preview dialog.
+  std::string GetFailedSetting() {

[Lei Zhang, 2014/07/17 23:31:05]

return a const std::string&, and make this method const.

[ivandavid, 2014/07/18 01:59:11]

Done.

+    return failed_setting_;
+  }
+
+ private:
+  // Listens for messages from the print preview dialog. Specifically, it
+  // listens for 'UILoadedForTest' and 'UIFailedLoadingForTest.'
+  class UIDoneLoadingMessageHandler : public content::WebUIMessageHandler {
+   public:
+    explicit UIDoneLoadingMessageHandler(PrintPreviewObserver* observer)
+        : observer_(observer) {}
+
+    virtual ~UIDoneLoadingMessageHandler() {}
+
+    // When a setting has been set succesfully, this is called and the observer
+    // is told to send the next setting to be set.
+    void HandleDone(const base::ListValue* /* args */) {
+      ASSERT_TRUE(observer_);
+      observer_->ManipulatePreviewSettings();
+    }
+
+    // Ends the test because a setting was not set successfully. Called when
+    // this class hears 'UIFailedLoadingForTest.'
+    void HandleFailure(const base::ListValue* /* args */) {
+      FAIL() << "Failed to set: " << observer_->GetFailedSetting();
+    }
+
+    // Allows this class to listen for the 'UILoadedForTest' and
+    // 'UIFailedLoadingForTest' messages. These messages are sent by the print
+    // preview dialog. 'UILoadedForTest' is sent when a setting has been
+    // successfully set and its effects have been finalized.
+    // 'UIFailedLoadingForTest' is sent when the setting could not be set. This
+    // causes the browser test to fail.
+    void RegisterMessages() OVERRIDE {
+      web_ui()->RegisterMessageCallback(
+          "UILoadedForTest",
+          base::Bind(&UIDoneLoadingMessageHandler::HandleDone,
+                     base::Unretained(this)));
+
+      web_ui()->RegisterMessageCallback(
+          "UIFailedLoadingForTest",
+          base::Bind(&UIDoneLoadingMessageHandler::HandleFailure,
+                     base::Unretained(this)));
+    }
+
+   private:
+    PrintPreviewObserver * const observer_;

[Lei Zhang, 2014/07/17 23:31:07]

PrintPreviewObserver*

[ivandavid, 2014/07/18 01:59:11]

Done.

+
+    DISALLOW_COPY_AND_ASSIGN(UIDoneLoadingMessageHandler);
+  };
+
+  // Called when the observer gets the IPC message stating that the page count
+  // is ready.
+  void OnDidGetPreviewPageCount(
+        const PrintHostMsg_DidGetPreviewPageCount_Params &params) {
+    WebContents* web_contents = GetDialog();
+    PrintPreviewUI* ui = GetUI();

[Lei Zhang, 2014/07/17 23:31:05]

I'd move this down to line 282 where it's actually being used.

[ivandavid, 2014/07/18 01:59:11]

Done.

+    ASSERT_TRUE(ui);
+    ASSERT_TRUE(ui->web_ui());
+    Observe(web_contents);
+    ASSERT_TRUE(web_contents);

[Lei Zhang, 2014/07/17 23:31:06]

I'd assert this before passing it to Observe(), not the other way around.

[ivandavid, 2014/07/18 01:59:11]

Done.

+
+    // The |ui->web_ui()| owns the message handler.
+    ui->web_ui()->AddMessageHandler(new UIDoneLoadingMessageHandler(this));
+    ui->web_ui()->CallJavascriptFunction("onEnableManipulateSettingsForTest");
+  }
+
+  void DidCloneToNewWebContents(WebContents* old_web_contents,
+                                WebContents* new_web_contents) OVERRIDE {
+    Observe(new_web_contents);
+  }
+
+  void WebContentsDestroyed() OVERRIDE {
+    EndLoop();
+  }
+
+  Browser* browser_;
+  base::Closure quit_closure_;
+  scoped_ptr<PrintPreviewSettings> settings_;
+
+  // State of the observer. The state indicates what message to send
+  // next. The state advances whenever the message handler calls
+  // ManipulatePreviewSettings() on the observer.
+  State state_;
+  std::string failed_setting_;
+
+  DISALLOW_COPY_AND_ASSIGN(PrintPreviewObserver);
+};
+
+class PrintPreviewPdfGeneratedBrowserTest : public InProcessBrowserTest {
+ public:
+  PrintPreviewPdfGeneratedBrowserTest() {}
+  virtual ~PrintPreviewPdfGeneratedBrowserTest() {}
+
+  // Navigates to the given web page, then initiates print preview and waits
+  // for all the settings to be set.
+  void NavigateAndPreview(const base::FilePath::StringType& file_name,
+                          const PrintPreviewSettings& settings) {
+    print_preview_observer_->SetPrintPreviewSettings(settings);
+    base::FilePath path(file_name);
+    GURL gurl = net::FilePathToFileURL(path);
+
+    ui_test_utils::NavigateToURL(browser(), gurl);
+
+    base::RunLoop loop;
+    print_preview_observer_->set_quit_closure(loop.QuitClosure());
+    chrome::Print(browser());
+    loop.Run();
+  }
+
+  // Prints the web page to a PDF. NavigateAndPreview must be called first.
+  void Print() {
+    ASSERT_FALSE(pdf_file_save_path_.empty());
+    base::RunLoop loop;
+    print_preview_observer_->set_quit_closure(loop.QuitClosure());
+    print_preview_observer_->GetUI()->SetSelectedFileForTesting(
+        pdf_file_save_path_);
+    loop.Run();
+    // Checks to see if the file exists and is readable. If the file doesn't
+    // exist, the test will fail. If it exists, but isn't readable, the test
+    // will keep polling until the file becomes readable. This is due to a
+    // problem on Windows where the file exists, but isn't readable, causing
+    // other ASSERT statements in this test to fail.
+    // TODO(ivandavid): Come up with a better way to do this.
+    ASSERT_TRUE(base::PathExists(pdf_file_save_path));
+    while (true) {
+      base::File pdf_file(
+          pdf_file_save_path_, base::File::FLAG_OPEN | base::File::FLAG_READ);
+      if (pdf_file.IsValid())
+          break;

[Lei Zhang, 2014/07/17 23:31:07]

indentation is off

[ivandavid, 2014/07/18 01:59:11]

Done.

+    }
+  }
+
+  // Initializes function pointers from the PDF library.
+  // Called once when browser test starts. The ibrary is closed when the browser

[Lei Zhang, 2014/07/17 23:31:06]

typo

[ivandavid, 2014/07/18 01:59:10]

Done.

+  // test ends.
+  void InitPdfFunctions() {
+    base::FilePath pdf_module_path;
+
+    ASSERT_TRUE(PathService::Get(chrome::FILE_PDF_PLUGIN, &pdf_module_path));
+    ASSERT_TRUE(base::PathExists(pdf_module_path));
+    pdf_lib_.Reset(base::LoadNativeLibrary(pdf_module_path, NULL));
+
+    ASSERT_TRUE(pdf_lib_.is_valid());
+    pdf_to_bitmap_func_ =
+        reinterpret_cast<PDFPageToBitmapProc>(
+            pdf_lib_.GetFunctionPointer("RenderPDFPageToBitmap"));
+
+    pdf_doc_info_func_ =
+        reinterpret_cast<GetPDFDocInfoProc>(
+            pdf_lib_.GetFunctionPointer("GetPDFDocInfo"));
+
+    pdf_page_size_func_ =
+        reinterpret_cast<GetPDFPageSizeByIndexProc>(
+            pdf_lib_.GetFunctionPointer("GetPDFPageSizeByIndex"));
+
+    ASSERT_TRUE(pdf_to_bitmap_func_);
+    ASSERT_TRUE(pdf_doc_info_func_);
+    ASSERT_TRUE(pdf_page_size_func_);
+  }
+
+  // Converts the PDF to a PNG file so that the layout test can do an image
+  // diff on this image and a reference image.
+  void PdfToPng() {
+    int num_pages;
+    double max_width_in_points = 0;
+    std::vector<uint8_t> bitmap_data;
+    double total_height_in_pixels = 0;
+    std::string pdf_data;
+
+    ASSERT_TRUE(base::ReadFileToString(pdf_file_save_path_, &pdf_data));
+    ASSERT_TRUE(pdf_doc_info_func_(pdf_data.data(),
+                                   pdf_data.size(),
+                                   &num_pages,
+                                   &max_width_in_points));
+
+    ASSERT_GT(num_pages, 0);
+    double max_width_in_pixels =
+        ConvertPointsToPixelDouble(max_width_in_points);
+
+    for (int i = 0; i < num_pages; ++i) {
+      double width_in_points, height_in_points;
+      ASSERT_TRUE(pdf_page_size_func_(pdf_data.data(),
+                                      pdf_data.size(),
+                                      i,
+                                      &width_in_points,
+                                      &height_in_points));
+
+      double width_in_pixels = ConvertPointsToPixelDouble(width_in_points);
+      double height_in_pixels = ConvertPointsToPixelDouble(height_in_points);
+
+      // The image will be rotated if |width_in_pixels| is greater than
+      // |height_in_pixels|. This is because the page will be rotated to fit
+      // within a piece of paper. Therefore, |width_in_pixels| and
+      // |height_in_pixels| have to be swapped or else they won't reflect the
+      // dimensions of the rotated page.
+      if (width_in_pixels > height_in_pixels)
+        std::swap(width_in_pixels, height_in_pixels);
+
+      total_height_in_pixels += height_in_pixels;
+      gfx::Rect rect(width_in_pixels, height_in_pixels);
+      PdfRenderSettings settings(rect, kDpi, true);
+
+      int int_max = std::numeric_limits<int>::max();
+      if (settings.area().width() > int_max / kColorChannels ||
+          settings.area().height() > int_max / (kColorChannels *
+              settings.area().width())) {
+        FAIL() << "The dimensions of the image are too large."
+               << "Decrease the DPI or the dimensions of the image.";
+      }
+
+      std::vector<uint8_t> page_bitmap_data(

[Lei Zhang, 2014/07/17 23:31:06]

Does it work of you make this a std::vector<uint32_t> and drop the
|kColorChannels| multiplier?

[ivandavid, 2014/07/18 01:59:10]

I will work on this later.

+          kColorChannels * settings.area().size().GetArea());
+
+      ASSERT_TRUE(pdf_to_bitmap_func_(pdf_data.data(),
+                                      pdf_data.size(),
+                                      i,
+                                      page_bitmap_data.data(),
+                                      settings.area().size().width(),
+                                      settings.area().size().height(),
+                                      settings.dpi(),
+                                      settings.dpi(),
+                                      true));
+      FillPng(&page_bitmap_data,
+              width_in_pixels,
+              max_width_in_pixels,
+              settings.area().size().height());
+      bitmap_data.insert(bitmap_data.end(),
+                         page_bitmap_data.begin(),
+                         page_bitmap_data.end());
+    }
+
+    CreatePng(bitmap_data, max_width_in_pixels, total_height_in_pixels);
+  }
+
+  // Fills out a bitmap with whitespace so that the image will correctly fit
+  // within a PNG that is wider than the bitmap itself.
+  void FillPng(std::vector<uint8_t>* bitmap,
+               int current_width,
+               int desired_width,
+               int height) {
+    ASSERT_TRUE(bitmap);
+    ASSERT_GT(height, 0);
+    ASSERT_LE(current_width, desired_width);
+
+    if (current_width == desired_width)
+      return;
+
+    int current_width_in_bytes = current_width * kColorChannels;
+    int desired_width_in_bytes = desired_width * kColorChannels;
+    const uint8_t kColorByte = 255;
+    std::vector<uint8_t> filled_bitmap(
+        desired_width * kColorChannels * height, kColorByte);
+    std::vector<uint8_t>::iterator filled_bitmap_it = filled_bitmap.begin();
+    std::vector<uint8_t>::iterator bitmap_it = bitmap->begin();
+
+    for (int i = 0; i < height; ++i) {
+      std::copy(

[ivandavid, 2014/07/17 22:27:47]

I used std::copy rather than memcpy because I was using iterators and its more
standard (I think).

+          bitmap_it, bitmap_it + current_width_in_bytes, filled_bitmap_it);
+      std::advance(bitmap_it, current_width_in_bytes);
+      std::advance(filled_bitmap_it, desired_width_in_bytes);
+    }
+
+    bitmap->assign(filled_bitmap.begin(), filled_bitmap.end());
+  }
+
+  // Sends the PNG image to the layout test framework for comparison.
+  void SendPng() {
+    // Send image header and |hash_| to the layout test framework.
+    std::cout << "Content-Type: image/png\n";
+    std::cout << "ActualHash: " << base::MD5DigestToBase16(hash_) << "\n";
+    std::cout << "Content-Length: " << output_.size() << "\n";
+
+    for (size_t i = 0; i < output_.size(); ++i)

[Lei Zhang, 2014/07/17 23:31:07]

Does this work?

std::copy(output_.begin(), output_.end(), std::ostream_iterator<unsigned
char>(std::cout, ""));

[ivandavid, 2014/07/18 01:59:10]

Wow. This is pretty cool, I never would've though to do a copy into the buffer.

[ivandavid, 2014/07/18 01:59:11]

Done.

+      std::cout << output_[i];
+
+    std::cout << "#EOF\n";
+    std::cout.flush();
+    std::cerr << "#EOF\n";
+    std::cerr.flush();
+  }
+
+  // Duplicates the tab that was created when the browser opened. This is done
+  // so that the observer can listen to the duplicated tab as soon as possible
+  // and start listening for messages related to print preview.
+  void DuplicateTab() {
+    WebContents* tab =
+        browser()->tab_strip_model()->GetActiveWebContents();
+    ASSERT_TRUE(tab);
+
+    print_preview_observer_.reset(new PrintPreviewObserver(browser(), tab));
+    chrome::DuplicateTab(browser());
+
+    WebContents* initiator =
+        browser()->tab_strip_model()->GetActiveWebContents();
+    ASSERT_TRUE(initiator);
+    ASSERT_NE(tab, initiator);
+  }
+
+  // Resets the test so that another web page can be printed. It also deletes
+  // the duplicated tab as it isn't needed anymore.
+  void Reset() {
+    output_.clear();
+    ASSERT_EQ(browser()->tab_strip_model()->count(), 2);

[Lei Zhang, 2014/07/17 23:31:06]

ASSERT_EQ()'s signature is ASSERT_EQ(expected, actual), so the arguments should
be reversed.

[ivandavid, 2014/07/18 01:59:11]

Done.

+    chrome::CloseTab(browser());
+    ASSERT_EQ(browser()->tab_strip_model()->count(), 1);
+  }
+
+  // Creates a temporary directory to store a text file that will be used for
+  // stdin to accept input from the layout test framework. A path for the PDF
+  // file is also created. The directory and files within it are automatically
+  // cleaned up once the test ends.
+  void SetupStdinAndSavePath() {
+    // Sets the filemode to binary because it will force |std::cout| to send LF
+    // rather than CRLF. Sending CRLF will cause an error message for the
+    // layout tests.
+#if defined(OS_WIN)
+    _setmode(_fileno(stdout), _O_BINARY);
+    _setmode(_fileno(stderr), _O_BINARY);
+#endif
+    // Sends a message to the layout test framework indicating indicating
+    // that the browser test has completed setting itself up. The layout
+    // test will then expect the file path for stdin.
+    base::FilePath tmp_path;
+    std::cout << "#READY\n";
+    std::cout.flush();
+
+    ASSERT_TRUE(tmp_dir_.CreateUniqueTempDir());

[Lei Zhang, 2014/07/17 23:31:05]

Didn't you mention in person that there exists an issue with this since the test
gets killed? Can you add a comment and mention it here?

[ivandavid, 2014/07/18 01:59:11]

I actually already fixed it. The python code cleans it up.

[Lei Zhang, 2014/07/18 02:11:01]

Cleans up |stdin_path| or |tmp_dir_.path()|, which is the parent of |stdin_path|
?

[ivandavid, 2014/07/18 02:30:26]

|tmp_dir_.path()| is cleaned up. I'll add a comment about it at line 629.

+    ASSERT_TRUE(base::CreateTemporaryFileInDir(tmp_dir_.path(), &tmp_path));
+    std::ifstream* in = new std::ifstream(tmp_path.value().c_str());
+    ASSERT_TRUE(in->is_open());
+    std::cin.rdbuf(in->rdbuf());
+
+    pdf_file_save_path_ =
+        tmp_dir_.path().Append(FILE_PATH_LITERAL("dummy.pdf"));
+
+    // Send the file path to the layout test framework so that it can
+    // communicate with this browser test.
+    std::cout << "StdinPath: " << tmp_path.value() << "\n";
+    std::cout << "#EOF\n";
+    std::cout.flush();
+  }
+
+ private:
+  // Generates a png from bitmap data and stores it in |output_|.
+  void CreatePng(

[Lei Zhang, 2014/07/17 23:31:06]

CreatePng(arg1,
          arg2,
          arg3);

[ivandavid, 2014/07/18 01:59:11]

Done.

+        const std::vector<uint8_t>& bitmap_data, int width, int height) {
+    std::string hash_data(bitmap_data.begin(), bitmap_data.end());

[Lei Zhang, 2014/07/17 23:31:07]

Do you really need to make a copy of |bitmap_data| ?

[ivandavid, 2014/07/18 01:59:11]

Done.

[ivandavid, 2014/07/18 01:59:11]

That was a holder over. Its gone.

+    base::MD5Sum(
+        static_cast<const void*>(hash_data.data()), hash_data.size(), &hash_);
+
+    gfx::Rect png_rect(width, height);
+
+    // tEXtchecksum looks funny, but that's what the layout test framework
+    // expects.
+    std::string comment_title("tEXtchecksum\x00");
+    gfx::PNGCodec::Comment hash_comment(comment_title,
+                                        base::MD5DigestToBase16(hash_));
+
+    std::vector<gfx::PNGCodec::Comment> comments;
+    comments.push_back(hash_comment);
+
+    ASSERT_TRUE(gfx::PNGCodec::Encode(bitmap_data.data(),
+                                      gfx::PNGCodec::FORMAT_BGRA,
+                                      png_rect.size(),
+                                      png_rect.size().width() * kColorChannels,
+                                      false,
+                                      comments,
+                                      &output_));
+  }
+
+  scoped_ptr<PrintPreviewObserver> print_preview_observer_;
+  base::FilePath pdf_file_save_path_;
+
+  // These typedefs are function pointers to pdflib functions that give
+  // information about the PDF as a whole and about specific pages.
+
+  // Converts the PDF to a bitmap.
+  typedef bool (*PDFPageToBitmapProc)(const void* pdf_buffer,
+                                      int pdf_buffer_size,
+                                      int page_number,
+                                      void* bitmap_buffer,
+                                      int bitmap_width,
+                                      int bitmap_height,
+                                      int dpi_x,
+                                      int dpi_y,
+                                      bool autorotate);
+
+  // Gets the page count and maximum page width of the PDF in points.
+  typedef bool (*GetPDFDocInfoProc)(const void* pdf_buffer,
+                                    int buffer_size,
+                                    int* pages_count,
+                                    double* max_page_width);
+
+  // Gets the dimensions of a specific page within a PDF.
+  typedef bool (*GetPDFPageSizeByIndexProc)(const void* pdf_buffer,
+                                            int buffer_size,
+                                            int index,
+                                            double* width,
+                                            double* height);
+
+  // Instantiations of the function pointers described above.
+  PDFPageToBitmapProc pdf_to_bitmap_func_;
+  GetPDFDocInfoProc pdf_doc_info_func_;
+  GetPDFPageSizeByIndexProc pdf_page_size_func_;
+
+  // Used to open up the libpdf.so, which contains the functions above.

[Lei Zhang, 2014/07/17 23:31:06]

s/libpdf.so/pdf plugin/ since it's not libpdf.so on Mac/Windows.

+  base::ScopedNativeLibrary pdf_lib_;
+
+  // Vector for storing the PNG to be sent to the layout test framework.
+  std::vector<unsigned char> output_;

[Lei Zhang, 2014/07/17 23:31:05]

Use uint8_t or uint32_t, whichever we decided to go with.

[Lei Zhang, 2014/07/17 23:31:06]

png_output_ ?

[ivandavid, 2014/07/18 01:59:10]

Done.

+
+  // Image hash of the bitmap that is turned into a PNG. The hash is put into
+  // the PNG as a comment, as it is needed by the layout test framework.
+  base::MD5Digest hash_;
+
+  // Temporary directory for storing the pdf and the file for stdin.
+  base::ScopedTempDir tmp_dir_;
+
+  DISALLOW_COPY_AND_ASSIGN(PrintPreviewPdfGeneratedBrowserTest);
+};
+
+IN_PROC_BROWSER_TEST_F(PrintPreviewPdfGeneratedBrowserTest,
+                       MANUAL_DummyTest) {

[Lei Zhang, 2014/07/17 23:31:06]

Can we give the test a better name than DummyTest?

[ivandavid, 2014/07/18 01:59:10]

I renamed it to LayoutTestDriver, since that's what it is.

[ivandavid, 2014/07/18 01:59:11]

Done.

+  // What this code is supposed to do:
+  // - Setup communication with the layout test framework
+  // - Print webpage to a pdf
+  // - Convert pdf to a png
+  // - Send png to layout test framework, where it doesn an image diff
+  //   on the image sent by this test and a reference image.
+  //
+  // Throughout this code, there will be printf statements. The layout test

[Lei Zhang, 2014/07/17 23:31:05]

there's no more printf statements.

[ivandavid, 2014/07/18 01:59:10]

Done.

+  // framework uses stdout to get data from the browser test and uses stdin
+  // to send data to the browser test. Writing "EOF\n" to |std::cout| indicates
+  // that whatever block of data that the test was expecting has been completely
+  // sent. Sometimes EOF is printed to stderr because the test will expect it
+  // from stderr in addition to stdout for certain blocks of data.
+  InitPdfFunctions();
+  SetupStdinAndSavePath();
+
+  // There is no way to determine how many tests are to be run ahead of time
+  // without undesirable changes to the layout test framework. However, that is
+  // ok since whenever all the tests have been run, the layout test framework
+  // calls SIGKILL on this process, ending the test. This will end the while
+  // loop and cause the test to clean up after itself. For this to work, the
+  // browsertest must be run with '--single_process' not '--single-process.'
+  while (true) {
+    std::string input;
+    std::getline(std::cin, input);
+    if (input.empty()) {
+      while (std::cin.eof()) {
+        std::cin.clear();
+        std::getline(std::cin, input);
+        if (!input.empty()) {
+          break;
+        }
+      }
+    }
+
+    base::FilePath::StringType file_extension = FILE_PATH_LITERAL(".pdf");
+    base::FilePath::StringType cmd;
+#if defined(OS_POSIX)
+    cmd = input;
+#elif defined(OS_WIN)
+    cmd = base::UTF8ToWide(temp);

[Lei Zhang, 2014/07/17 23:31:06]

s/temp/input/

[ivandavid, 2014/07/18 01:59:10]

Done.

+#endif
+
+    DuplicateTab();
+    PrintPreviewSettings settings(
+        true,
+        "",
+        false,
+        false,
+        DEFAULT_MARGINS,
+        cmd.find(file_extension) != base::FilePath::StringType::npos);
+
+    // Splits the command sent by the layout test framework. The first command
+    // is always the file path to use for the test. The rest isn't relevant,
+    // so it can be ignored. The separator for the commands is an apostrophe.
+    std::vector<base::FilePath::StringType> cmd_arguments;
+    base::SplitString(cmd, '\'', &cmd_arguments);
+
+    // 1 Needs to be cast because ASSERT_GE can't compare unsigned and signed

[Lei Zhang, 2014/07/17 23:31:06]

This comment is no longer relevant.

[ivandavid, 2014/07/18 01:59:11]

Done.

+    // numbers.
+    ASSERT_GE(cmd_arguments.size(), 1U);
+    base::FilePath::StringType test_name(cmd_arguments[0]);
+    NavigateAndPreview(test_name, settings);
+    Print();
+    PdfToPng();
+
+    // Message to the layout test framework indicating that it should start
+    // waiting for the image data, as there is no more text data to be read.
+    // There actually isn't any text data at all, however because the layout
+    // test framework requires it, a message has to be sent to stop it from
+    // waiting for this message and start waiting for the image data.
+    std::cout << "#EOF\n";
+    std::cout.flush();
+
+    SendPng();
+    Reset();
+  }
+}
+
+}  // namespace printing