Revert 78666 - Cleanup NativeMetafile (win) interface and EMF class.

- Rename CreateDc to Init() and remove unused argument (all non-test calls were CreateDc(NULL, NULL).  [This matches cross platform interface.]
- Remove CreateFileBackedDc from the NativeMetafile interface and make InitToFile() in the EMF class.
- Remove CreateFromFile from the NativeMetafile interface and make it InitFromFile() in the EMF class.
- Move the CloseEmf method into the destructor, making the Emf class a use once class (matches actual use).

BUG=NONE
TEST=NONE

Review URL: http://codereview.chromium.org/6695013

TBR=vandebo@chromium.org
Review URL: http://codereview.chromium.org/6712030

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@78669 0039d316-1c4b-4281-b951-d872f2087c98

11 files changed, 150 insertions, 106 deletions

diff --git a/chrome/common/common_param_traits_unittest.cc b/chrome/common/common_param_traits_unittest.cc
index f9aabe1..7928032 100644
--- a/chrome/common/common_param_traits_unittest.cc
+++ b/chrome/common/common_param_traits_unittest.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2006-2008 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.
 
@@ -241,7 +241,7 @@ TEST(IPCMessageTest, Metafile) {
       printing::NativeMetafileFactory::CreateMetafile());
   RECT test_rect = {0, 0, 100, 100};
   // Create a metafile using the screen DC as a reference.
-  metafile->Init();
+  metafile->CreateDc(NULL, NULL);
   metafile->Close();
 
   IPC::Message msg(1, 2, IPC::Message::PRIORITY_NORMAL);
diff --git a/chrome/renderer/print_web_view_helper_win.cc b/chrome/renderer/print_web_view_helper_win.cc
index f248da94..72e3399 100644
--- a/chrome/renderer/print_web_view_helper_win.cc
+++ b/chrome/renderer/print_web_view_helper_win.cc
@@ -71,7 +71,7 @@ void PrintWebViewHelper::PrintPage(const ViewMsg_PrintPage_Params& params,
   // Each metafile contains a single page.
   scoped_ptr<printing::NativeMetafile> metafile(
       printing::NativeMetafileFactory::CreateMetafile());
-  metafile->Init();
+  metafile->CreateDc(NULL, NULL);
   DCHECK(metafile->context());
   skia::PlatformDevice::InitializeDC(metafile->context());
 
@@ -108,6 +108,7 @@ void PrintWebViewHelper::PrintPage(const ViewMsg_PrintPage_Params& params,
                                    &(page_params.metafile_data_handle))) {
     page_params.data_size = 0;
   }
+  metafile->CloseEmf();
   if (!Send(new ViewHostMsg_DuplicateSection(
           routing_id(),
           page_params.metafile_data_handle,
@@ -138,7 +139,7 @@ void PrintWebViewHelper::CreatePreviewDocument(
   // http://code.google.com/p/chromium/issues/detail?id=62889
   scoped_ptr<printing::NativeMetafile> metafile(
       printing::NativeMetafileFactory::CreateMetafile());
-  metafile->Init();
+  metafile->CreateDc(NULL, NULL);
   DCHECK(metafile->context());
   skia::PlatformDevice::InitializeDC(metafile->context());
 
@@ -180,6 +181,7 @@ void PrintWebViewHelper::CreatePreviewDocument(
     preview_params.data_size = 0;
     preview_params.expected_pages_count = 0;
   }
+  metafile->CloseEmf();
   if (!Send(new ViewHostMsg_DuplicateSection(
           routing_id(),
           preview_params.metafile_data_handle,
@@ -287,7 +289,7 @@ void PrintWebViewHelper::RenderPage(
     HBRUSH whiteBrush = static_cast<HBRUSH>(GetStockObject(WHITE_BRUSH));
     FillRect(bitmap_dc, &rect, whiteBrush);
 
-    metafile2->Init();
+    metafile2->CreateDc(NULL, NULL);
     HDC hdc = metafile2->context();
     DCHECK(hdc);
     skia::PlatformDevice::InitializeDC(hdc);
diff --git a/chrome/service/cloud_print/print_system_win.cc b/chrome/service/cloud_print/print_system_win.cc
index e963403..01caaa8 100644
--- a/chrome/service/cloud_print/print_system_win.cc
+++ b/chrome/service/cloud_print/print_system_win.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 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.
 
@@ -26,7 +26,7 @@
 #include "printing/backend/print_backend.h"
 #include "printing/backend/print_backend_consts.h"
 #include "printing/backend/win_helper.h"
-#include "printing/emf_win.h"
+#include "printing/native_metafile.h"
 #include "printing/page_range.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/gfx/rect.h"
@@ -448,7 +448,7 @@ class PrintSystemWin : public PrintSystem {
 
       // ServiceUtilityProcessHost::Client implementation.
       virtual void OnRenderPDFPagesToMetafileSucceeded(
-          const printing::Emf& metafile,
+          const printing::NativeMetafile& metafile,
           int highest_rendered_page_number) {
         metafile.SafePlayback(printer_dc_.Get());
         bool done_printing = (highest_rendered_page_number !=
diff --git a/chrome/service/service_utility_process_host.cc b/chrome/service/service_utility_process_host.cc
index fb5080c..a340d8d 100644
--- a/chrome/service/service_utility_process_host.cc
+++ b/chrome/service/service_utility_process_host.cc
@@ -20,7 +20,8 @@
 #if defined(OS_WIN)
 #include "base/scoped_ptr.h"
 #include "base/win/scoped_handle.h"
-#include "printing/emf_win.h"
+#include "printing/native_metafile_factory.h"
+#include "printing/native_metafile.h"
 #endif
 
 ServiceUtilityProcessHost::ServiceUtilityProcessHost(
@@ -203,15 +204,15 @@ void ServiceUtilityProcessHost::Client::MetafileAvailable(
   if (!scratch_metafile_dir.Set(metafile_path.DirName()))
     LOG(WARNING) << "Unable to set scratch metafile directory";
 #if defined(OS_WIN)
-  // It's important that metafile is declared after scratch_metafile_dir so
-  // that the metafile destructor closes the file before the ScopedTempDir
-  // destructor tries to remove the directory.
-  printing::Emf metafile;
-  if (!metafile.InitFromFile(metafile_path)) {
+  scoped_ptr<printing::NativeMetafile> metafile(
+      printing::NativeMetafileFactory::CreateMetafile());
+  if (!metafile->CreateFromFile(metafile_path)) {
     OnRenderPDFPagesToMetafileFailed();
   } else {
-    OnRenderPDFPagesToMetafileSucceeded(metafile,
+    OnRenderPDFPagesToMetafileSucceeded(*metafile,
                                         highest_rendered_page_number);
+    // Close it so that ScopedTempDir can delete the folder.
+    metafile->CloseEmf();
   }
 #endif  // defined(OS_WIN)
 }
diff --git a/chrome/service/service_utility_process_host.h b/chrome/service/service_utility_process_host.h
index ad7eb3e..b770e1a 100644
--- a/chrome/service/service_utility_process_host.h
+++ b/chrome/service/service_utility_process_host.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 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.
 
@@ -21,6 +21,7 @@
 #include "base/task.h"
 #include "ipc/ipc_channel.h"
 #include "chrome/service/service_child_process_host.h"
+#include "printing/native_metafile.h"
 
 class CommandLine;
 class ScopedTempDir;
@@ -34,7 +35,6 @@ class Rect;
 }  // namespace gfx
 
 namespace printing {
-class Emf;
 struct PageRange;
 struct PrinterCapsAndDefaults;
 }  // namespace printing
@@ -57,7 +57,7 @@ class ServiceUtilityProcessHost : public ServiceChildProcessHost {
     // Called when at least one page in the specified PDF has been rendered
     // successfully into |metafile|.
     virtual void OnRenderPDFPagesToMetafileSucceeded(
-        const printing::Emf& metafile,
+        const printing::NativeMetafile& metafile,
         int highest_rendered_page_number) {}
     // Called when no page in the passed in PDF could be rendered.
     virtual void OnRenderPDFPagesToMetafileFailed() {}
diff --git a/chrome/utility/utility_thread.cc b/chrome/utility/utility_thread.cc
index 9fc175c6..7b665ae 100644
--- a/chrome/utility/utility_thread.cc
+++ b/chrome/utility/utility_thread.cc
@@ -30,7 +30,8 @@
 #include "app/win/iat_patch_function.h"
 #include "base/scoped_ptr.h"
 #include "base/win/scoped_handle.h"
-#include "printing/emf_win.h"
+#include "printing/native_metafile_factory.h"
+#include "printing/native_metafile.h"
 #endif
 
 namespace {
@@ -256,17 +257,18 @@ bool UtilityThread::RenderPDFToWinMetafile(
   if (!get_info_proc(&buffer.front(), buffer.size(), &total_page_count, NULL))
     return false;
 
-  printing::Emf metafile;
-  metafile.InitToFile(metafile_path);
+  scoped_ptr<printing::NativeMetafile> metafile(
+      printing::NativeMetafileFactory::CreateMetafile());
+  metafile->CreateFileBackedDc(NULL, NULL, metafile_path);
   // Since we created the metafile using the screen DPI (but we actually want
   // the PDF DLL to print using the passed in render_dpi, we apply the following
   // transformation.
-  SetGraphicsMode(metafile.context(), GM_ADVANCED);
+  SetGraphicsMode(metafile->context(), GM_ADVANCED);
   XFORM xform = {0};
   int screen_dpi = GetDeviceCaps(GetDC(NULL), LOGPIXELSX);
   xform.eM11 = xform.eM22 =
       static_cast<float>(screen_dpi) / static_cast<float>(render_dpi);
-  ModifyWorldTransform(metafile.context(), &xform, MWT_LEFTMULTIPLY);
+  ModifyWorldTransform(metafile->context(), &xform, MWT_LEFTMULTIPLY);
 
   bool ret = false;
   std::vector<printing::PageRange>::const_iterator iter;
@@ -274,18 +276,18 @@ bool UtilityThread::RenderPDFToWinMetafile(
     for (int page_number = iter->from; page_number <= iter->to; ++page_number) {
       if (page_number >= total_page_count)
         break;
-      metafile.StartPage();
+      metafile->StartPage();
       if (render_proc(&buffer.front(), buffer.size(), page_number,
-                      metafile.context(), render_dpi, render_dpi,
+                      metafile->context(), render_dpi, render_dpi,
                       render_area.x(), render_area.y(), render_area.width(),
                       render_area.height(), true, false, true, true))
         if (*highest_rendered_page_number < page_number)
           *highest_rendered_page_number = page_number;
         ret = true;
-      metafile.FinishPage();
+      metafile->FinishPage();
     }
   }
-  metafile.Close();
+  metafile->Close();
   return ret;
 }
 #endif  // defined(OS_WIN)
diff --git a/content/plugin/webplugin_delegate_stub.cc b/content/plugin/webplugin_delegate_stub.cc
index a0fa40a..cf26fc0 100644
--- a/content/plugin/webplugin_delegate_stub.cc
+++ b/content/plugin/webplugin_delegate_stub.cc
@@ -273,7 +273,7 @@ void WebPluginDelegateStub::OnPrint(base::SharedMemoryHandle* shared_memory,
 #if defined(OS_WIN)
   scoped_ptr<printing::NativeMetafile> metafile(
       printing::NativeMetafileFactory::CreateMetafile());
-  if (!metafile->Init()) {
+  if (!metafile->CreateDc(NULL, NULL)) {
     NOTREACHED();
     return;
   }
diff --git a/printing/emf_win.cc b/printing/emf_win.cc
index 7e3dbeb..6fea291 100644
--- a/printing/emf_win.cc
+++ b/printing/emf_win.cc
@@ -50,39 +50,41 @@ Emf::Emf() : emf_(NULL), hdc_(NULL) {
 }
 
 Emf::~Emf() {
-  DCHECK(!hdc_);
-  if (emf_)
-    DeleteEnhMetaFile(emf_);
+  CloseEmf();
+  DCHECK(!emf_ && !hdc_);
 }
 
-bool Emf::InitToFile(const FilePath& metafile_path) {
+bool Emf::InitFromData(const void* src_buffer, uint32 src_buffer_size) {
   DCHECK(!emf_ && !hdc_);
-  hdc_ = CreateEnhMetaFile(NULL, metafile_path.value().c_str(), NULL, NULL);
-  DCHECK(hdc_);
-  return hdc_ != NULL;
+  emf_ = SetEnhMetaFileBits(src_buffer_size,
+                            reinterpret_cast<const BYTE*>(src_buffer));
+  return emf_ != NULL;
 }
 
-bool Emf::InitFromFile(const FilePath& metafile_path) {
+bool Emf::CreateDc(HDC sibling, const RECT* rect) {
   DCHECK(!emf_ && !hdc_);
-  emf_ = GetEnhMetaFile(metafile_path.value().c_str());
-  DCHECK(emf_);
-  return emf_ != NULL;
+  hdc_ = CreateEnhMetaFile(sibling, NULL, rect, NULL);
+  DCHECK(hdc_);
+  return hdc_ != NULL;
 }
 
-bool Emf::Init() {
+bool Emf::CreateFileBackedDc(HDC sibling, const RECT* rect,
+                             const FilePath& path) {
   DCHECK(!emf_ && !hdc_);
-  hdc_ = CreateEnhMetaFile(NULL, NULL, NULL, NULL);
+  DCHECK(!path.empty());
+  hdc_ = CreateEnhMetaFile(sibling, path.value().c_str(), rect, NULL);
   DCHECK(hdc_);
   return hdc_ != NULL;
 }
 
-bool Emf::InitFromData(const void* src_buffer, uint32 src_buffer_size) {
+bool Emf::CreateFromFile(const FilePath& metafile_path) {
   DCHECK(!emf_ && !hdc_);
-  emf_ = SetEnhMetaFileBits(src_buffer_size,
-                            reinterpret_cast<const BYTE*>(src_buffer));
+  emf_ = GetEnhMetaFile(metafile_path.value().c_str());
+  DCHECK(emf_);
   return emf_ != NULL;
 }
 
+
 bool Emf::Close() {
   DCHECK(!emf_ && hdc_);
   emf_ = CloseEnhMetaFile(hdc_);
@@ -91,6 +93,14 @@ bool Emf::Close() {
   return emf_ != NULL;
 }
 
+void Emf::CloseEmf() {
+  DCHECK(!hdc_);
+  if (emf_) {
+    DeleteEnhMetaFile(emf_);
+    emf_ = NULL;
+  }
+}
+
 bool Emf::Playback(HDC hdc, const RECT* rect) const {
   DCHECK(emf_ && !hdc_);
   RECT bounds;
diff --git a/printing/emf_win.h b/printing/emf_win.h
index 0503e6f..5150356 100644
--- a/printing/emf_win.h
+++ b/printing/emf_win.h
@@ -27,20 +27,10 @@ class Emf : public NativeMetafile {
   class Enumerator;
   struct EnumerationContext;
 
-  // Generates a virtual HDC that will record every GDI commands and compile
-  // it in a EMF data stream.
-  Emf();
   virtual ~Emf();
 
-  // Generates a new metafile that will record every GDI command, and will
-  // be saved to |metafile_path|.
-  virtual bool InitToFile(const FilePath& metafile_path);
-
-  // Initializes the Emf with the data in |metafile_path|.
-  virtual bool InitFromFile(const FilePath& metafile_path);
-
   // NativeMetafile methods.
-  virtual bool Init();
+  virtual bool Init() { return true; }
   virtual bool InitFromData(const void* src_buffer, uint32 src_buffer_size);
 
   virtual bool StartPage();
@@ -67,6 +57,14 @@ class Emf : public NativeMetafile {
     return hdc_;
   }
 
+  virtual bool CreateDc(HDC sibling, const RECT* rect);
+  virtual bool CreateFileBackedDc(HDC sibling,
+                                  const RECT* rect,
+                                  const FilePath& path);
+  virtual bool CreateFromFile(const FilePath& file_path);
+
+  virtual void CloseEmf();
+
   virtual bool Playback(HDC hdc, const RECT* rect) const;
   virtual bool SafePlayback(HDC hdc) const;
 
@@ -76,7 +74,16 @@ class Emf : public NativeMetafile {
     return emf_;
   }
 
+ protected:
+  Emf();
+
  private:
+  friend class NativeMetafileFactory;
+  FRIEND_TEST_ALL_PREFIXES(EmfTest, DC);
+  FRIEND_TEST_ALL_PREFIXES(EmfTest, FileBackedDC);
+  FRIEND_TEST_ALL_PREFIXES(EmfPrintingTest, Enumerate);
+  FRIEND_TEST_ALL_PREFIXES(EmfPrintingTest, PageBreak);
+
   // Playbacks safely one EMF record.
   static int CALLBACK SafePlaybackProc(HDC hdc,
                                        HANDLETABLE* handle_table,
diff --git a/printing/emf_win_unittest.cc b/printing/emf_win_unittest.cc
index 16ca82e..2f4e2ae 100644
--- a/printing/emf_win_unittest.cc
+++ b/printing/emf_win_unittest.cc
@@ -43,26 +43,26 @@ namespace printing {
 
 TEST(EmfTest, DC) {
   // Simplest use case.
-  uint32 size;
+  printing::Emf emf;
+  RECT rect = {100, 100, 200, 200};
+  HDC hdc = CreateCompatibleDC(NULL);
+  EXPECT_TRUE(hdc != NULL);
+  EXPECT_TRUE(emf.CreateDc(hdc, &rect));
+  EXPECT_TRUE(emf.context() != NULL);
+  // In theory, you'd use the HDC with GDI functions here.
+  EXPECT_TRUE(emf.Close());
+  uint32 size = emf.GetDataSize();
+  EXPECT_EQ(size, EMF_HEADER_SIZE);
   std::vector<BYTE> data;
-  {
-    printing::Emf emf;
-    EXPECT_TRUE(emf.Init());
-    EXPECT_TRUE(emf.context() != NULL);
-    // An empty EMF is invalid, so we put at least a rectangle in it.
-    ::Rectangle(emf.context(), 10, 10, 190, 190);
-    EXPECT_TRUE(emf.Close());
-    size = emf.GetDataSize();
-    EXPECT_GT(size, EMF_HEADER_SIZE);
-    EXPECT_TRUE(emf.GetData(&data));
-    EXPECT_EQ(data.size(), size);
-  }
+  EXPECT_TRUE(emf.GetData(&data));
+  EXPECT_EQ(data.size(), size);
+  emf.CloseEmf();
+  EXPECT_TRUE(DeleteDC(hdc));
 
   // Playback the data.
-  printing::Emf emf;
-  EXPECT_TRUE(emf.InitFromData(&data.front(), size));
-  HDC hdc = CreateCompatibleDC(NULL);
+  hdc = CreateCompatibleDC(NULL);
   EXPECT_TRUE(hdc);
+  EXPECT_TRUE(emf.InitFromData(&data.front(), size));
   RECT output_rect = {0, 0, 10, 10};
   EXPECT_TRUE(emf.Playback(hdc, &output_rect));
   EXPECT_TRUE(DeleteDC(hdc));
@@ -126,31 +126,28 @@ TEST_F(EmfPrintingTest, PageBreak) {
       CreateDC(L"WINSPOOL", L"UnitTest Printer", NULL, NULL));
   if (!dc.Get())
     return;
-  uint32 size;
-  std::vector<BYTE> data;
-  {
-    printing::Emf emf;
-    EXPECT_TRUE(emf.Init());
-    EXPECT_TRUE(emf.context() != NULL);
-    int pages = 3;
-    while (pages) {
-      EXPECT_TRUE(emf.StartPage());
-      ::Rectangle(emf.context(), 10, 10, 190, 190);
-      EXPECT_TRUE(emf.FinishPage());
-      --pages;
-    }
-    EXPECT_TRUE(emf.Close());
-    size = emf.GetDataSize();
-    EXPECT_TRUE(emf.GetData(&data));
-    EXPECT_EQ(data.size(), size);
+  printing::Emf emf;
+  EXPECT_TRUE(emf.CreateDc(dc.Get(), NULL));
+  EXPECT_TRUE(emf.context() != NULL);
+  int pages = 3;
+  while (pages) {
+    EXPECT_TRUE(emf.StartPage());
+    ::Rectangle(emf.context(), 10, 10, 190, 190);
+    EXPECT_TRUE(emf.FinishPage());
+    --pages;
   }
+  EXPECT_TRUE(emf.Close());
+  uint32 size = emf.GetDataSize();
+  std::vector<BYTE> data;
+  EXPECT_TRUE(emf.GetData(&data));
+  EXPECT_EQ(data.size(), size);
+  emf.CloseEmf();
 
   // Playback the data.
   DOCINFO di = {0};
   di.cbSize = sizeof(DOCINFO);
   di.lpszDocName = L"Test Job";
   int job_id = ::StartDoc(dc.Get(), &di);
-  printing::Emf emf;
   EXPECT_TRUE(emf.InitFromData(&data.front(), size));
   EXPECT_TRUE(emf.SafePlayback(dc.Get()));
   ::EndDoc(dc.Get());
@@ -163,39 +160,41 @@ TEST_F(EmfPrintingTest, PageBreak) {
   }
 }
 
-TEST(EmfTest, FileBackedEmf) {
+TEST(EmfTest, FileBackedDC) {
   // Simplest use case.
+  printing::Emf emf;
+  RECT rect = {100, 100, 200, 200};
+  HDC hdc = CreateCompatibleDC(NULL);
+  EXPECT_TRUE(hdc != NULL);
   ScopedTempDir scratch_metafile_dir;
   ASSERT_TRUE(scratch_metafile_dir.CreateUniqueTempDir());
   FilePath metafile_path;
   EXPECT_TRUE(file_util::CreateTemporaryFileInDir(scratch_metafile_dir.path(),
                                                   &metafile_path));
-  uint32 size;
+  EXPECT_TRUE(emf.CreateFileBackedDc(hdc, &rect, metafile_path));
+  EXPECT_TRUE(emf.context() != NULL);
+  // In theory, you'd use the HDC with GDI functions here.
+  EXPECT_TRUE(emf.Close());
+
+  uint32 size = emf.GetDataSize();
+  EXPECT_EQ(size, EMF_HEADER_SIZE);
   std::vector<BYTE> data;
-  {
-    printing::Emf emf;
-    EXPECT_TRUE(emf.InitToFile(metafile_path));
-    EXPECT_TRUE(emf.context() != NULL);
-    // An empty EMF is invalid, so we put at least a rectangle in it.
-    ::Rectangle(emf.context(), 10, 10, 190, 190);
-    EXPECT_TRUE(emf.Close());
-    size = emf.GetDataSize();
-    EXPECT_GT(size, EMF_HEADER_SIZE);
-    EXPECT_TRUE(emf.GetData(&data));
-    EXPECT_EQ(data.size(), size);
-  }
+  EXPECT_TRUE(emf.GetData(&data));
+  EXPECT_EQ(data.size(), size);
+  emf.CloseEmf();
   int64 file_size = 0;
   file_util::GetFileSize(metafile_path, &file_size);
   EXPECT_EQ(size, file_size);
+  EXPECT_TRUE(DeleteDC(hdc));
 
   // Playback the data.
-  HDC hdc = CreateCompatibleDC(NULL);
+  hdc = CreateCompatibleDC(NULL);
   EXPECT_TRUE(hdc);
-  printing::Emf emf;
-  EXPECT_TRUE(emf.InitFromFile(metafile_path));
+  EXPECT_TRUE(emf.CreateFromFile(metafile_path));
   RECT output_rect = {0, 0, 10, 10};
   EXPECT_TRUE(emf.Playback(hdc, &output_rect));
   EXPECT_TRUE(DeleteDC(hdc));
+  emf.CloseEmf();
 }
 
 }  // namespace printing
diff --git a/printing/native_metafile.h b/printing/native_metafile.h
index 08b3277..a076b32 100644
--- a/printing/native_metafile.h
+++ b/printing/native_metafile.h
@@ -101,6 +101,29 @@ class NativeMetafile {
   virtual gfx::NativeDrawingContext context() const = 0;
 
 #if defined(OS_WIN)
+  // Generates a virtual HDC that will record every GDI commands and compile it
+  // in a EMF data stream.
+  // hdc is used to setup the default DPI and color settings. hdc is optional.
+  // rect specifies the dimensions (in .01-millimeter units) of the EMF. rect is
+  // optional.
+  virtual bool CreateDc(gfx::NativeDrawingContext sibling,
+                        const RECT* rect) = 0;
+
+  // Similar to the above method but the metafile is backed by a file.
+  virtual bool CreateFileBackedDc(gfx::NativeDrawingContext sibling,
+                                  const RECT* rect,
+                                  const FilePath& path) = 0;
+
+  // TODO(maruel): CreateFromFile(). If ever used. Maybe users would like to
+  // have the ability to save web pages to an EMF file? Afterward, it is easy to
+  // convert to PDF or PS.
+  // Load a metafile fromdisk.
+  virtual bool CreateFromFile(const FilePath& metafile_path) = 0;
+
+  // Closes the HDC created by CreateDc() and generates the compiled EMF
+  // data.
+  virtual void CloseEmf() = 0;
+
   // "Plays" the EMF buffer in a HDC. It is the same effect as calling the
   // original GDI function that were called when recording the EMF. |rect| is in
   // "logical units" and is optional. If |rect| is NULL, the natural EMF bounds