Allow multiple base::MessagePumpForUI instances to be created simultanenously on Windows.

The current implementation of base::MessagePumpForUI on Windows registers a window class with a predefined name in order to create a message-only window. The window class is unregistered when base::MessagePumpForUI is deleted. This causes issues when two or more instances of base::MessagePumpForUI are created/destroyed simultanenously on different threads. For instance once thread can unregister the window class right before the other thread is trying to create a window using this class.

The CL addresses this problem by switching MessageWindow to implement a message-only window. It also moves MessageWindow from remoting/host/win to base/win along with the corresponding unit test.

MessageWindow registers a uniquely named window class per MessageWindow instance making sure that different MessageWindow objects do not share any resources. In the future this can be optimized further by registering a common window class shared by all MessageWindow objects in a thread-safe manner (by using LazyInstance for example).

BUG=241939

Review URL: https://chromiumcodereview.appspot.com/15261005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@201955 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 239 insertions, 0 deletions

diff --git a/base/win/message_window.cc b/base/win/message_window.cc
new file mode 100644
index 0000000..10d20ec
--- /dev/null
+++ b/base/win/message_window.cc
@@ -0,0 +1,111 @@
+// Copyright 2013 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 "base/win/message_window.h"
+
+#include "base/logging.h"
+#include "base/process_util.h"
+#include "base/stringprintf.h"
+#include "base/utf_string_conversions.h"
+#include "base/win/wrapped_window_proc.h"
+
+const char kClassNameFormat[] = "Chrome_MessageWindow_%p";
+
+namespace base {
+namespace win {
+
+MessageWindow::MessageWindow()
+    : atom_(0),
+      instance_(NULL),
+      window_(NULL) {
+  class_name_ = base::StringPrintf(kClassNameFormat, this);
+  instance_ = base::GetModuleFromAddress(static_cast<WNDPROC>(
+      &base::win::WrappedWindowProc<WindowProc>));
+}
+
+MessageWindow::~MessageWindow() {
+  DCHECK(CalledOnValidThread());
+
+  if (window_ != NULL) {
+    DestroyWindow(window_);
+    window_ = NULL;
+  }
+
+  if (atom_ != 0) {
+    UnregisterClass(MAKEINTATOM(atom_), instance_);
+    atom_ = 0;
+  }
+}
+
+bool MessageWindow::Create(Delegate* delegate) {
+  DCHECK(CalledOnValidThread());
+  DCHECK(!atom_);
+  DCHECK(!window_);
+
+  // Register a separate window class for each instance of |MessageWindow|.
+  string16 class_name = UTF8ToUTF16(class_name_);
+  WNDCLASSEX window_class;
+  window_class.cbSize = sizeof(window_class);
+  window_class.style = 0;
+  window_class.lpfnWndProc = &base::win::WrappedWindowProc<WindowProc>;
+  window_class.cbClsExtra = 0;
+  window_class.cbWndExtra = 0;
+  window_class.hInstance = instance_;
+  window_class.hIcon = NULL;
+  window_class.hCursor = NULL;
+  window_class.hbrBackground = NULL;
+  window_class.lpszMenuName = NULL;
+  window_class.lpszClassName = class_name.c_str();
+  window_class.hIconSm = NULL;
+  atom_ = RegisterClassEx(&window_class);
+  if (atom_ == 0) {
+    LOG_GETLASTERROR(ERROR)
+        << "Failed to register the window class '" << class_name_ << "'";
+    return false;
+  }
+
+  window_ = CreateWindow(MAKEINTATOM(atom_), 0, 0, 0, 0, 0, 0, HWND_MESSAGE, 0,
+                         instance_, delegate);
+  if (!window_) {
+    LOG_GETLASTERROR(ERROR) << "Failed to create a message-only window";
+    return false;
+  }
+
+  return true;
+}
+
+// static
+LRESULT CALLBACK MessageWindow::WindowProc(HWND hwnd,
+                                           UINT message,
+                                           WPARAM wparam,
+                                           LPARAM lparam) {
+  Delegate* delegate = NULL;
+
+  // Set up the delegate before handling WM_CREATE.
+  if (message == WM_CREATE) {
+    CREATESTRUCT* cs = reinterpret_cast<CREATESTRUCT*>(lparam);
+    delegate = reinterpret_cast<Delegate*>(cs->lpCreateParams);
+
+    // Store pointer to the delegate to the window's user data.
+    SetLastError(ERROR_SUCCESS);
+    LONG_PTR result = SetWindowLongPtr(
+        hwnd, GWLP_USERDATA, reinterpret_cast<LONG_PTR>(delegate));
+    CHECK(result != 0 || GetLastError() == ERROR_SUCCESS);
+  } else {
+    delegate = reinterpret_cast<Delegate*>(GetWindowLongPtr(hwnd,
+                                                            GWLP_USERDATA));
+  }
+
+  // Handle the message.
+  if (delegate) {
+    LRESULT message_result;
+    if (delegate->HandleMessage(hwnd, message, wparam, lparam, &message_result))
+      return message_result;
+  }
+
+  return DefWindowProc(hwnd, message, wparam, lparam);
+}
+
+}  // namespace win
+}  // namespace base
diff --git a/base/win/message_window.h b/base/win/message_window.h
new file mode 100644
index 0000000..9cc4573
--- /dev/null
+++ b/base/win/message_window.h
@@ -0,0 +1,67 @@
+// Copyright 2013 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.
+
+#ifndef BASE_WIN_MESSAGE_WINDOW_H_
+#define BASE_WIN_MESSAGE_WINDOW_H_
+
+#include <windows.h>
+
+#include <string>
+
+#include "base/base_export.h"
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/threading/non_thread_safe.h"
+
+namespace base {
+namespace win {
+
+// Implements a message-only window.
+class BASE_EXPORT MessageWindow : base::NonThreadSafe {
+ public:
+  // Handles incoming window messages.
+  class BASE_EXPORT Delegate {
+   public:
+    virtual ~Delegate() {}
+
+    virtual bool HandleMessage(HWND hwnd,
+                               UINT message,
+                               WPARAM wparam,
+                               LPARAM lparam,
+                               LRESULT* result) = 0;
+  };
+
+  MessageWindow();
+  ~MessageWindow();
+
+  // Registers the window class and creates the window. The incoming messages
+  // will be handled by |delegate|. |delegate| must outlive |this|.
+  bool Create(Delegate* delegate);
+
+  HWND hwnd() const { return window_; }
+
+ private:
+  // Invoked by the OS to process incoming window messages.
+  static LRESULT CALLBACK WindowProc(HWND hwnd, UINT message, WPARAM wparam,
+                                     LPARAM lparam);
+
+  // Atom representing the registered window class.
+  ATOM atom_;
+
+  // MessageWindow class name.
+  std::string class_name_;
+
+  // Instance of the module containing the window procedure.
+  HINSTANCE instance_;
+
+  // Handle of the input window.
+  HWND window_;
+
+  DISALLOW_COPY_AND_ASSIGN(MessageWindow);
+};
+
+}  // namespace win
+}  // namespace base
+
+#endif  // BASE_WIN_MESSAGE_WINDOW_H_
diff --git a/base/win/message_window_unittest.cc b/base/win/message_window_unittest.cc
new file mode 100644
index 0000000..5910a7b
--- /dev/null
+++ b/base/win/message_window_unittest.cc
@@ -0,0 +1,61 @@
+// Copyright (c) 2012 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 "base/win/message_window.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+namespace {
+
+class MessageWindowDelegate : public win::MessageWindow::Delegate {
+ public:
+  MessageWindowDelegate();
+  virtual ~MessageWindowDelegate();
+
+  // MessageWindow::Delegate interface.
+  virtual bool HandleMessage(HWND hwnd,
+                             UINT message,
+                             WPARAM wparam,
+                             LPARAM lparam,
+                             LRESULT* result) OVERRIDE;
+};
+
+MessageWindowDelegate::MessageWindowDelegate() {
+}
+
+MessageWindowDelegate::~MessageWindowDelegate() {
+}
+
+bool MessageWindowDelegate::HandleMessage(
+    HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam, LRESULT* result) {
+  // Return |wparam| as the result of WM_USER message.
+  if (message == WM_USER) {
+    *result = wparam;
+    return true;
+  }
+
+  return false;
+}
+
+}  // namespace
+
+// Checks that a window can be created.
+TEST(MessageWindowTest, Create) {
+  MessageWindowDelegate delegate;
+  win::MessageWindow window;
+  EXPECT_TRUE(window.Create(&delegate));
+}
+
+// Verifies that the created window can receive messages.
+TEST(MessageWindowTest, SendMessage) {
+  MessageWindowDelegate delegate;
+  win::MessageWindow window;
+  EXPECT_TRUE(window.Create(&delegate));
+
+  EXPECT_EQ(SendMessage(window.hwnd(), WM_USER, 100, 0), 100);
+}
+
+}  // namespace base