Revert 209047 "ProcessSingleton now uses base::win::MessageWindo..."

> ProcessSingleton now uses base::win::MessageWindow to create a message-only window.
> 
> Collateral changes:
>   - base::win::MessageWindow registes a single window class used by all message-only windows it creates. The class is registered via base::LazyInstance.
>   - Added base::win::MessageWindow::FindWindow() wrapper used to find other message-only windows, including the other created by a different process.
>   - Removed chrome::kMessageWindowClass constant.
> 
> Review URL: https://chromiumcodereview.appspot.com/17615003

TBR=alexeypa@chromium.org

Review URL: https://codereview.chromium.org/18040003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@209232 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 43 insertions, 86 deletions

diff --git a/base/win/message_window.cc b/base/win/message_window.cc
index fa6381b..8a9c287 100644
--- a/base/win/message_window.cc
+++ b/base/win/message_window.cc
@@ -4,68 +4,20 @@
 
 #include "base/win/message_window.h"
 
-#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/process_util.h"
+#include "base/strings/string16.h"
+#include "base/strings/stringprintf.h"
 #include "base/win/wrapped_window_proc.h"
 
-const wchar_t kMessageWindowClassName[] = L"Chrome_MessageWindow";
+const wchar_t kClassNameFormat[] = L"Chrome_MessageWindow_%p";
 
 namespace base {
 namespace win {
 
-// Used along with LazyInstance to register a window class for message-only
-// windows created by MessageWindow.
-class MessageWindow::WindowClass {
- public:
-  WindowClass();
-  ~WindowClass();
-
-  ATOM atom() { return atom_; }
-  HINSTANCE instance() { return instance_; }
-
- private:
-  ATOM atom_;
-  HINSTANCE instance_;
-
-  DISALLOW_COPY_AND_ASSIGN(WindowClass);
-};
-
-static LazyInstance<MessageWindow::WindowClass> g_window_class =
-    LAZY_INSTANCE_INITIALIZER;
-
-MessageWindow::WindowClass::WindowClass()
-    : atom_(0),
-      instance_(base::GetModuleFromAddress(&MessageWindow::WindowProc)) {
-  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 = kMessageWindowClassName;
-  window_class.hIconSm = NULL;
-  atom_ = RegisterClassEx(&window_class);
-  if (atom_ == 0) {
-    LOG_GETLASTERROR(ERROR)
-        << "Failed to register the window class for a message-only window";
-  }
-}
-
-MessageWindow::WindowClass::~WindowClass() {
-  if (atom_ != 0) {
-    BOOL result = UnregisterClass(MAKEINTATOM(atom_), instance_);
-    DCHECK(result);
-  }
-}
-
 MessageWindow::MessageWindow()
-    : window_(NULL) {
+    : atom_(0),
+      window_(NULL) {
 }
 
 MessageWindow::~MessageWindow() {
@@ -75,6 +27,13 @@ MessageWindow::~MessageWindow() {
     BOOL result = DestroyWindow(window_);
     DCHECK(result);
   }
+
+  if (atom_ != 0) {
+    BOOL result = UnregisterClass(
+        MAKEINTATOM(atom_),
+        base::GetModuleFromAddress(&MessageWindow::WindowProc));
+    DCHECK(result);
+  }
 }
 
 bool MessageWindow::Create(const MessageCallback& message_callback) {
@@ -86,23 +45,41 @@ bool MessageWindow::CreateNamed(const MessageCallback& message_callback,
   return DoCreate(message_callback, window_name.c_str());
 }
 
-// static
-HWND MessageWindow::FindWindow(const string16& window_name) {
-  return FindWindowEx(HWND_MESSAGE, NULL, kMessageWindowClassName,
-                      window_name.c_str());
-}
-
 bool MessageWindow::DoCreate(const MessageCallback& message_callback,
-                             const wchar_t* window_name) {
+                           const wchar_t* window_name) {
   DCHECK(CalledOnValidThread());
+  DCHECK(!atom_);
   DCHECK(message_callback_.is_null());
   DCHECK(!window_);
 
   message_callback_ = message_callback;
 
-  WindowClass& window_class = g_window_class.Get();
-  window_ = CreateWindow(MAKEINTATOM(window_class.atom()), window_name, 0, 0, 0,
-                         0, 0, HWND_MESSAGE, 0, window_class.instance(), this);
+  // Register a separate window class for each instance of |MessageWindow|.
+  string16 class_name = base::StringPrintf(kClassNameFormat, this);
+  HINSTANCE instance = base::GetModuleFromAddress(&MessageWindow::WindowProc);
+
+  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 for a message-only window";
+    return false;
+  }
+
+  window_ = CreateWindow(MAKEINTATOM(atom_), window_name, 0, 0, 0, 0, 0,
+                         HWND_MESSAGE, 0, instance, this);
   if (!window_) {
     LOG_GETLASTERROR(ERROR) << "Failed to create a message-only window";
     return false;
diff --git a/base/win/message_window.h b/base/win/message_window.h
index d255eec..4fd5074 100644
--- a/base/win/message_window.h
+++ b/base/win/message_window.h
@@ -20,9 +20,6 @@ namespace win {
 // Implements a message-only window.
 class BASE_EXPORT MessageWindow : public base::NonThreadSafe {
  public:
-  // Used to register a process-wide message window class.
-  class WindowClass;
-
   // Implement this callback to handle messages received by the message window.
   // If the callback returns |false|, the first four parameters are passed to
   // DefWindowProc(). Otherwise, |*result| is returned by the window procedure.
@@ -44,14 +41,7 @@ class BASE_EXPORT MessageWindow : public base::NonThreadSafe {
 
   HWND hwnd() const { return window_; }
 
-  // Retrieves a handle of the first message-only window with matching
-  // |windows_name|.
-  static HWND FindWindow(const string16& window_name);
-
  private:
-  // Give |WindowClass| access to WindowProc().
-  friend class WindowClass;
-
   // Contains the actual window creation code.
   bool DoCreate(const MessageCallback& message_callback,
                 const wchar_t* window_name);
@@ -60,6 +50,9 @@ class BASE_EXPORT MessageWindow : public base::NonThreadSafe {
   static LRESULT CALLBACK WindowProc(HWND hwnd, UINT message, WPARAM wparam,
                                      LPARAM lparam);
 
+  // Atom representing the registered window class.
+  ATOM atom_;
+
   // Invoked to handle messages received by the window.
   MessageCallback message_callback_;
 
diff --git a/base/win/message_window_unittest.cc b/base/win/message_window_unittest.cc
index 00248bf..c933ef7 100644
--- a/base/win/message_window_unittest.cc
+++ b/base/win/message_window_unittest.cc
@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 #include "base/bind.h"
-#include "base/guid.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/win/message_window.h"
 #include "testing/gmock/include/gmock/gmock.h"
@@ -32,7 +31,6 @@ TEST(MessageWindowTest, Create) {
   EXPECT_TRUE(window.Create(base::Bind(&HandleMessage)));
 }
 
-// Checks that a named window can be created.
 TEST(MessageWindowTest, CreateNamed) {
   win::MessageWindow window;
   EXPECT_TRUE(window.CreateNamed(base::Bind(&HandleMessage),
@@ -47,15 +45,4 @@ TEST(MessageWindowTest, SendMessage) {
   EXPECT_EQ(SendMessage(window.hwnd(), WM_USER, 100, 0), 100);
 }
 
-// Verifies that a named window can be found by name.
-TEST(MessageWindowTest, FindWindow) {
-  string16 name = UTF8ToUTF16(base::GenerateGUID());
-  win::MessageWindow window;
-  EXPECT_TRUE(window.CreateNamed(base::Bind(&HandleMessage), name));
-
-  HWND hwnd = win::MessageWindow::FindWindow(name);
-  EXPECT_TRUE(hwnd != NULL);
-  EXPECT_EQ(SendMessage(hwnd, WM_USER, 200, 0), 200);
-}
-
 }  // namespace base