Add a helper process to Chrome Frame to allow for non-administrative installs. The helper process registers a hook dll that performs the necessary BHO injection instead of registering it in HKLM.

BUG=53127
TEST=Non-admin CF installs work.

Review URL: http://codereview.chromium.org/3158036

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@57860 0039d316-1c4b-4281-b951-d872f2087c98

12 files changed, 669 insertions, 23 deletions

diff --git a/chrome_frame/bho_loader.cc b/chrome_frame/bho_loader.cc
new file mode 100644
index 0000000..fb8f71d
--- /dev/null
+++ b/chrome_frame/bho_loader.cc
@@ -0,0 +1,93 @@
+// 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.
+
+#include "chrome_frame/bho_loader.h"
+
+#include <atlbase.h>
+#include <atlcomcli.h>
+#include <exdisp.h>
+
+#include "chrome_frame/chrome_frame_helper_util.h"
+#include "chrome_frame/event_hooker.h"
+#include "chrome_tab.h"  // NOLINT
+
+
+// Describes the window class we look for.
+const wchar_t kStatusBarWindowClass[] = L"msctls_statusbar32";
+
+BHOLoader::BHOLoader() : hooker_(new EventHooker()) {
+}
+
+BHOLoader::~BHOLoader() {
+  if (hooker_) {
+    delete hooker_;
+    hooker_ = NULL;
+  }
+}
+
+void BHOLoader::OnHookEvent(DWORD event, HWND window) {
+  // Step 1: Make sure that we are in a process named iexplore.exe.
+  if (IsNamedProcess(L"iexplore.exe")) {
+    // Step 2: Check to see if the window is of the right class.
+    // IE loads BHOs in the WM_CREATE handler of the tab window approximately
+    // after it creates the status bar window. To be as close to IE as possible
+    // in our simulation on BHO loading, we watch for the status bar to be
+    // created and do our simulated BHO loading at that time.
+    if (IsWindowOfClass(window, kStatusBarWindowClass)) {
+      HWND parent_window = GetParent(window);
+      // Step 3:
+      // Parent window of status bar window is the web browser window. Try to
+      // get its IWebBrowser2 interface
+      CComPtr<IWebBrowser2> browser;
+      UtilGetWebBrowserObjectFromWindow(parent_window, __uuidof(browser),
+                                        reinterpret_cast<void**>(&browser));
+      if (browser) {
+        // TODO(robertshield): We may need to find a way to prevent doing this
+        // twice. A marker of some kind would do. Ask during review for good
+        // suggestions.
+
+        // Step 4:
+        // We have the IWebBrowser2 interface. Now create the BHO instance
+        CComPtr<IObjectWithSite> bho_object;
+        HRESULT error_code =  bho_object.CoCreateInstance(CLSID_ChromeFrameBHO,
+                                                          NULL,
+                                                          CLSCTX_INPROC_SERVER);
+
+        if (SUCCEEDED(error_code) && bho_object) {
+          // Step 5:
+          // Initialize the BHO by calling SetSite and passing it IWebBrowser2
+          error_code = bho_object->SetSite(browser);
+          if (SUCCEEDED(error_code)) {
+            // Step 6:
+            // Now add the BHO to the collection of automation objects. This
+            // will ensure that BHO will be accessible from the web pages as
+            // any other BHO. Importantly, it will make sure that our BHO
+            // will be cleaned up at the right time along with other BHOs.
+            wchar_t bho_clsid_as_string[MAX_PATH] = {0};
+            StringFromGUID2(CLSID_ChromeFrameBHO, bho_clsid_as_string,
+                            ARRAYSIZE(bho_clsid_as_string));
+
+            CComBSTR bho_clsid_as_string_bstr(bho_clsid_as_string);
+            CComVariant object_variant(bho_object);
+
+            browser->PutProperty(bho_clsid_as_string_bstr, object_variant);
+          }
+        }
+      }
+    }
+  }
+}
+
+bool BHOLoader::StartHook() {
+  return hooker_->StartHook();
+}
+
+void BHOLoader::StopHook() {
+  hooker_->StopHook();
+}
+
+BHOLoader* BHOLoader::GetInstance() {
+  static BHOLoader loader;
+  return &loader;
+}
diff --git a/chrome_frame/bho_loader.h b/chrome_frame/bho_loader.h
new file mode 100644
index 0000000..0503375
--- /dev/null
+++ b/chrome_frame/bho_loader.h
@@ -0,0 +1,39 @@
+// 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.
+
+#ifndef CHROME_FRAME_BHO_LOADER_H_
+#define CHROME_FRAME_BHO_LOADER_H_
+
+#include <windows.h>
+
+// Forward.
+class EventHooker;
+
+// This class simulates BHO loading in an IE process. It watches for the
+// creation of a specific window and then retrieves the web browser object
+// for that window and simulates loading of the BHO.
+class BHOLoader {
+ public:
+  BHOLoader();
+  ~BHOLoader();
+
+  // Callback invoked on receipt of an accessibility event.
+  void OnHookEvent(DWORD event, HWND window);
+
+  // Call this to install event hooks that will trigger on window creation
+  // and reparenting. Returns true if the hooks are successfully installed,
+  // false otherwise.
+  bool StartHook();
+
+  // Call this to remove the event hooks that are installed by StartHook().
+  void StopHook();
+
+  // Retrieve the BHOLoader instance. Note that this is NOT thread-safe.
+  static BHOLoader* GetInstance();
+
+ private:
+  EventHooker* hooker_;
+};
+
+#endif  // CHROME_FRAME_BHO_LOADER_H_
diff --git a/chrome_frame/chrome_frame.gyp b/chrome_frame/chrome_frame.gyp
index 0580d81..c005104 100644
--- a/chrome_frame/chrome_frame.gyp
+++ b/chrome_frame/chrome_frame.gyp
@@ -758,6 +758,8 @@
         'chrome_frame_utils',
         'xulrunner_sdk',
         'chrome_frame_launcher.gyp:chrome_launcher',
+        'chrome_frame_launcher.gyp:chrome_frame_helper',
+        'chrome_frame_launcher.gyp:chrome_frame_helper_dll',
         '../chrome/chrome.gyp:chrome_version_header',
         '../chrome/chrome.gyp:common',
         '../chrome/chrome.gyp:utility',
@@ -783,7 +785,7 @@
       'include_dirs': [
         # To allow including "chrome_tab.h"
         '<(INTERMEDIATE_DIR)',
-        '<(INTERMEDIATE_DIR)/../chrome_frame',
+        '<(INTERMEDIATE_DIR)/../npchrome_frame',
       ],
       'conditions': [
         ['OS=="win"', {
diff --git a/chrome_frame/chrome_frame_helper_dll.cc b/chrome_frame/chrome_frame_helper_dll.cc
new file mode 100644
index 0000000..2c3a4a8
--- /dev/null
+++ b/chrome_frame/chrome_frame_helper_dll.cc
@@ -0,0 +1,28 @@
+// 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.
+
+// chrome_frame_helper_dll.cc : Implementation of a helper DLL that initializes
+// a listener for WinEvent hooks on load.
+//
+// Calling the StartUserModeBrowserInjection will set an in-context WinEvent
+// hook that will cause this DLL to get loaded in any process that sends
+// EVENT_OBJECT_CREATE accessibility events. This is a poor substitute to
+// getting in via vetted means (i.e. real BHO registration).
+
+#include "chrome_frame/bho_loader.h"
+#include "chrome_frame/chrome_frame_helper_util.h"
+
+STDAPI StartUserModeBrowserInjection() {
+  return BHOLoader::GetInstance()->StartHook() ? S_OK : E_FAIL;
+}
+
+STDAPI StopUserModeBrowserInjection() {
+  BHOLoader::GetInstance()->StopHook();
+  return S_OK;
+}
+
+BOOL APIENTRY DllMain(HMODULE module, DWORD reason_for_call, void* reserved) {
+  return TRUE;
+}
+
diff --git a/chrome_frame/chrome_frame_helper_dll.def b/chrome_frame/chrome_frame_helper_dll.def
new file mode 100644
index 0000000..54f7f36
--- /dev/null
+++ b/chrome_frame/chrome_frame_helper_dll.def
@@ -0,0 +1,5 @@
+LIBRARY  "chrome_frame_helper.dll"

+

+EXPORTS
+	StartUserModeBrowserInjection    PRIVATE
+	StopUserModeBrowserInjection     PRIVATE
diff --git a/chrome_frame/chrome_frame_helper_main.cc b/chrome_frame/chrome_frame_helper_main.cc
new file mode 100644
index 0000000..f4369a88
--- /dev/null
+++ b/chrome_frame/chrome_frame_helper_main.cc
@@ -0,0 +1,131 @@
+// 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.
+//
+// chrome_frame_helper_main.cc : The .exe that bootstraps the
+// chrome_frame_helper.dll.
+//
+// This is a small exe that loads the hook dll to set the event hooks and then
+// waits in a message loop. It is intended to be shut down by looking for a
+// window with the class and title
+// kChromeFrameHelperWindowClassName and kChromeFrameHelperWindowName and then
+// sending that window a WM_CLOSE message.
+//
+
+#include <crtdbg.h>
+#include <windows.h>
+
+// Window class and window names.
+const wchar_t kChromeFrameHelperWindowClassName[] =
+    L"ChromeFrameHelperWindowClass";
+const wchar_t kChromeFrameHelperWindowName[] =
+    L"ChromeFrameHelperWindowName";
+
+// Small helper class that assists in loading the DLL that contains code
+// to register our event hook callback. Automatically removes the hook and
+// unloads the DLL on destruction.
+class HookDllLoader {
+ public:
+  HookDllLoader() : dll_(NULL), start_proc_(NULL), stop_proc_(NULL) {}
+  ~HookDllLoader() {
+    if (dll_) {
+      Unload();
+    }
+  }
+
+  bool Load() {
+    dll_ = LoadLibrary(L"chrome_frame_helper.dll");
+    if (dll_) {
+      start_proc_ = GetProcAddress(dll_, "StartUserModeBrowserInjection");
+      stop_proc_ = GetProcAddress(dll_, "StopUserModeBrowserInjection");
+    }
+
+    bool result = true;
+    if (!start_proc_ || !stop_proc_) {
+      _ASSERTE(L"failed to load hook dll.");
+      result = false;
+    } else {
+      if (FAILED(start_proc_())) {
+        _ASSERTE(L"failed to initialize hook dll.");
+        result = false;
+      }
+    }
+    return result;
+  }
+
+  void Unload() {
+    if (stop_proc_) {
+      stop_proc_();
+    }
+    if (dll_) {
+      FreeLibrary(dll_);
+    }
+  }
+
+ private:
+  HMODULE dll_;
+  PROC start_proc_;
+  PROC stop_proc_;
+};
+
+
+LRESULT CALLBACK ChromeFrameHelperWndProc(HWND hwnd,
+                                          UINT message,
+                                          WPARAM wparam,
+                                          LPARAM lparam) {
+  switch (message) {
+    case WM_DESTROY:
+      PostQuitMessage(0);
+      break;
+    default:
+      return ::DefWindowProc(hwnd, message, wparam, lparam);
+  }
+  return 0;
+}
+
+HWND RegisterAndCreateWindow(HINSTANCE hinstance) {
+  WNDCLASSEX wcex = {0};
+  wcex.cbSize         = sizeof(WNDCLASSEX);
+  wcex.lpfnWndProc    = ChromeFrameHelperWndProc;
+  wcex.hInstance      = GetModuleHandle(NULL);
+  wcex.hbrBackground  = reinterpret_cast<HBRUSH>(COLOR_WINDOW+1);
+  wcex.lpszClassName  = kChromeFrameHelperWindowClassName;
+  RegisterClassEx(&wcex);
+
+  HWND hwnd = CreateWindow(kChromeFrameHelperWindowClassName,
+      kChromeFrameHelperWindowName, WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, 0,
+      CW_USEDEFAULT, 0, NULL, NULL, hinstance, NULL);
+
+  return hwnd;
+}
+
+int APIENTRY wWinMain(HINSTANCE hinstance, HINSTANCE, wchar_t*, int show_cmd) {
+  // TODO(robertshield): Before this actually gets used, add breakpad
+  // integration.
+
+  // Create a window with a known class and title just to listen for WM_CLOSE
+  // messages that will shut us down.
+  HWND hwnd = RegisterAndCreateWindow(hinstance);
+  _ASSERTE(hwnd);
+
+  // Load the hook dll, and set the event hooks.
+  HookDllLoader loader;
+  bool loaded = loader.Load();
+  _ASSERTE(loaded);
+
+  if (loaded) {
+    MSG msg;
+    BOOL ret;
+    // Main message loop:
+    while ((ret = GetMessage(&msg, NULL, 0, 0))) {
+      if (ret == -1) {
+        break;
+      } else {
+        TranslateMessage(&msg);
+        DispatchMessage(&msg);
+      }
+    }
+  }
+
+  return 0;
+}
diff --git a/chrome_frame/chrome_frame_helper_util.cc b/chrome_frame/chrome_frame_helper_util.cc
new file mode 100644
index 0000000..d246881
--- /dev/null
+++ b/chrome_frame/chrome_frame_helper_util.cc
@@ -0,0 +1,88 @@
+// 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.
+
+#include "chrome_frame/chrome_frame_helper_util.h"
+
+#include <shlwapi.h>
+
+const wchar_t kGetBrowserMessage[] = L"GetAutomationObject";
+
+bool UtilIsWebBrowserWindow(HWND window_to_check) {
+  bool is_browser_window = false;
+
+  if (!IsWindow(window_to_check)) {
+    return is_browser_window;
+  }
+
+  static wchar_t* known_ie_window_classes[] = {
+    L"IEFrame",
+    L"TabWindowClass"
+  };
+
+  for (int i = 0; i < ARRAYSIZE(known_ie_window_classes); i++) {
+    if (IsWindowOfClass(window_to_check, known_ie_window_classes[i])) {
+     is_browser_window = true;
+     break;
+    }
+  }
+
+  return is_browser_window;
+}
+
+HRESULT UtilGetWebBrowserObjectFromWindow(HWND window,
+                                          REFIID iid,
+                                          void** web_browser_object) {
+  if (NULL == web_browser_object) {
+    return E_POINTER;
+  }
+
+  // Check whether this window is really a web browser window.
+  if (UtilIsWebBrowserWindow(window)) {
+    // IWebBroswer2 interface pointer can be retrieved from the browser
+    // window by simply sending a registered message "GetAutomationObject"
+    // Note that since we are sending a message to parent window make sure that
+    // it is in the same thread.
+    if (GetWindowThreadProcessId(window, NULL) != GetCurrentThreadId()) {
+      return E_UNEXPECTED;
+    }
+
+    static const ULONG get_browser_message =
+        RegisterWindowMessageW(kGetBrowserMessage);
+
+    *web_browser_object =
+        reinterpret_cast<void*>(SendMessage(window,
+                                            get_browser_message,
+                                            reinterpret_cast<WPARAM>(&iid),
+                                            NULL));
+    if (NULL != *web_browser_object) {
+      return S_OK;
+    }
+  } else {
+    return E_INVALIDARG;
+  }
+  return E_NOINTERFACE;
+}
+
+
+bool IsWindowOfClass(HWND window_to_check, const wchar_t* window_class) {
+  bool window_matches = false;
+  const int buf_size = MAX_PATH;
+  wchar_t buffer[buf_size] = {0};
+  DWORD dwRetSize = GetClassNameW(window_to_check, buffer, buf_size);
+  // If the window name is any longer than this, it isn't the one we want.
+  if (dwRetSize < (buf_size - 1)) {
+    if (0 == lstrcmpiW(window_class, buffer)) {
+     window_matches = true;
+    }
+  }
+  return window_matches;
+}
+
+
+bool IsNamedProcess(const wchar_t* process_name) {
+  wchar_t file_path[2048] = {0};
+  GetModuleFileName(NULL, file_path, 2047);
+  wchar_t* file_name = PathFindFileName(file_path);
+  return (0 == lstrcmpiW(file_name, process_name));
+}
diff --git a/chrome_frame/chrome_frame_helper_util.h b/chrome_frame/chrome_frame_helper_util.h
new file mode 100644
index 0000000..f204debd
--- /dev/null
+++ b/chrome_frame/chrome_frame_helper_util.h
@@ -0,0 +1,43 @@
+// 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.
+
+#ifndef CHROME_FRAME_CHROME_FRAME_HELPER_UTIL_H_
+#define CHROME_FRAME_CHROME_FRAME_HELPER_UTIL_H_
+
+#include <windows.h>
+
+// Compare the given class name with the known window class names for
+// internet explorer browser windows.
+//
+// @param [in] window_to_check handle to the window to be checked
+//
+// @return true if the window class matches known class names for IE browser.
+//
+bool UtilIsWebBrowserWindow(HWND window_to_check);
+
+// A utility function that retrieves the specified web browser COM interface
+// from the web browser window. The passed in window must be the web browser
+// window (class name "IEFrame" in IE6 and "TabWindowClass" in IE7)
+// @param[in] window The web browser window whose COM object is to be fetched
+// @param[in] iid    The IID of the interface to be fetched
+// @param[out] web_browser_object
+//                   The requested interface pointer to the web browser object
+//                   is returned in this variable upon success
+//
+HRESULT UtilGetWebBrowserObjectFromWindow(HWND window,
+                                          REFIID iid,
+                                          void** web_browser_object);
+
+// Checks to see whether the passed in window is of the class specified.
+// of the heirarchy list
+// @param hwnd_to_match        [in]  The handle of the window that is to be
+//                                   matched.
+// @param window_class         [in]  The window class to match against.
+//
+bool IsWindowOfClass(HWND hwnd_to_match, const wchar_t* window_class);
+
+// Returns true if the current process name is process_name, false otherwise.
+bool IsNamedProcess(const wchar_t* process_name);
+
+#endif  // CHROME_FRAME_CHROME_FRAME_HELPER_UTIL_H_
diff --git a/chrome_frame/chrome_frame_helper_version.rc b/chrome_frame/chrome_frame_helper_version.rc
new file mode 100644
index 0000000..126207d
--- /dev/null
+++ b/chrome_frame/chrome_frame_helper_version.rc
@@ -0,0 +1,50 @@
+#include "version.h"

+

+#ifdef APSTUDIO_INVOKED

+# error Don't open this in the GUI, it'll be massacred on save.

+#endif // APSTUDIO_INVOKED

+

+/////////////////////////////////////////////////////////////////////////////

+//

+// Version

+//

+

+VS_VERSION_INFO VERSIONINFO

+ FILEVERSION CHROME_VERSION

+ PRODUCTVERSION CHROME_VERSION

+ FILEFLAGSMASK 0x17L

+#ifdef _DEBUG

+ FILEFLAGS 0x1L

+#else

+ FILEFLAGS 0x0L

+#endif

+ FILEOS 0x4L

+ FILETYPE 0x2L

+ FILESUBTYPE 0x0L

+BEGIN

+    BLOCK "StringFileInfo"

+    BEGIN

+        // Note that Firefox 3.0 requires the charset to be 04e4 (multi-lingual).

+        BLOCK "040904e4"

+        BEGIN

+            VALUE "CompanyName", COMPANY_FULLNAME_STRING

+            VALUE "CompanyShortName", COMPANY_SHORTNAME_STRING

+            VALUE "ProductName", "Google Chrome Frame"

+            VALUE "ProductShortName", "ChromeFrame"

+            VALUE "ProductVersion", CHROME_VERSION_STRING

+            VALUE "FileDescription", "Chrome Frame renders the Web of the future in the browsers of the past. It's like strapping a rocket engine to a minivan."

+            VALUE "FileVersion", CHROME_VERSION_STRING

+            VALUE "InternalName", "Google Chrome Frame"

+            VALUE "LegalCopyright", COPYRIGHT_STRING

+            VALUE "FileExtents", "chromeframe"

+            VALUE "FileOpenName", "chromeframe"

+            VALUE "LastChange", LASTCHANGE_STRING

+            VALUE "Official Build", OFFICIAL_BUILD_STRING

+        END

+    END

+    BLOCK "VarFileInfo"

+    BEGIN

+        // Note that Firefox 3.0 requires the charset to be 1252 (multi-lingual).

+        VALUE "Translation", 0x409, 1252

+    END

+END

diff --git a/chrome_frame/chrome_frame_launcher.gyp b/chrome_frame/chrome_frame_launcher.gyp
index 0e94c55..9a3d7a0 100644
--- a/chrome_frame/chrome_frame_launcher.gyp
+++ b/chrome_frame/chrome_frame_launcher.gyp
@@ -37,6 +37,29 @@
       # all our own includes are relative to src/
       '..',
     ],
+    'configurations': {
+      'Release_Base': {
+        # Set flags to unconditionally optimize chrome_frame_launcher.exe
+        # for release builds.
+        'msvs_settings': {
+          'VCLinkerTool': {
+            'LinkTimeCodeGeneration': '1',
+          },
+          'VCCLCompilerTool': {
+            'Optimization': '3',
+            'InlineFunctionExpansion': '2',
+            'EnableIntrinsicFunctions': 'true',
+            'FavorSizeOrSpeed': '2',
+            'OmitFramePointers': 'true',
+            'EnableFiberSafeOptimizations': 'true',
+            'WholeProgramOptimization': 'true',
+          },
+          'VCLibrarianTool': {
+            'AdditionalOptions': ['/ltcg', '/expectedoutputsize:120000000'],
+          },
+        },
+      },
+    },
   },
   'targets': [
     {
@@ -67,28 +90,78 @@
             'shlwapi.lib',
           ],
         },
-      },
-      'configurations': {
-        'Release_Base': {
-          # Set flags to unconditionally optimize chrome_frame_launcher.exe
-          # for release builds.
-          'msvs_settings': {
-            'VCLinkerTool': {
-              'LinkTimeCodeGeneration': '1',
-            },
-            'VCCLCompilerTool': {
-              'Optimization': '3',
-              'InlineFunctionExpansion': '2',
-              'EnableIntrinsicFunctions': 'true',
-              'FavorSizeOrSpeed': '2',
-              'OmitFramePointers': 'true',
-              'EnableFiberSafeOptimizations': 'true',
-              'WholeProgramOptimization': 'true',
-            },
-            'VCLibrarianTool': {
-              'AdditionalOptions': ['/ltcg', '/expectedoutputsize:120000000'],
-            },
-          },
+      },      
+    },
+    {
+      'target_name': 'chrome_frame_helper',
+      'type': 'executable',
+      'msvs_guid': 'BF4FFA36-2F66-4B65-9A91-AB7EC08D1042',
+      'dependencies': [
+        '../breakpad/breakpad.gyp:breakpad_handler',
+        '../chrome/chrome.gyp:chrome_version_header',
+        'chrome_frame_helper_dll',
+      ],
+      'resource_include_dirs': [
+        '<(INTERMEDIATE_DIR)',
+        '<(SHARED_INTERMEDIATE_DIR)',
+      ],
+      'include_dirs': [
+        # To allow including "chrome_tab.h"
+        '<(INTERMEDIATE_DIR)',
+        '<(INTERMEDIATE_DIR)/../chrome_frame',
+      ],
+      'sources': [
+        'chrome_frame_helper_main.cc',
+        'chrome_frame_helper_version.rc',
+      ],
+      'msvs_settings': {
+        'VCLinkerTool': {
+          'OutputFile':
+              '$(OutDir)\\servers\\$(ProjectName).exe',
+          # Set /SUBSYSTEM:WINDOWS since this is not a command-line program.
+          'SubSystem': '2',
+        },
+      },      
+    },
+    {
+      'target_name': 'chrome_frame_helper_dll',
+      'type': 'shared_library',
+      'msvs_guid': '5E80032F-7033-4661-9016-D98268244783',
+      'dependencies': [
+        '../chrome/chrome.gyp:chrome_version_header',
+      ],
+      'resource_include_dirs': [
+        '<(INTERMEDIATE_DIR)',
+        '<(SHARED_INTERMEDIATE_DIR)',
+      ],
+      'include_dirs': [
+        # To allow including "chrome_tab.h"
+        '<(INTERMEDIATE_DIR)',
+        '<(INTERMEDIATE_DIR)/../chrome_frame',
+      ],
+      'sources': [
+        'bho_loader.cc',
+        'bho_loader.h',
+        'chrome_frame_helper_dll.cc',
+        'chrome_frame_helper_dll.def',
+        'chrome_frame_helper_util.cc',
+        'chrome_frame_helper_util.h',
+        'chrome_frame_helper_version.rc',
+        'chrome_tab.h',
+        'chrome_tab.idl',
+        'event_hooker.cc',
+        'event_hooker.h',
+        'iids.cc',
+      ],
+      'msvs_settings': {
+        'VCLinkerTool': {
+          'OutputFile':
+              '$(OutDir)\\servers\\chrome_frame_helper.dll',
+          # Set /SUBSYSTEM:WINDOWS since this is not a command-line program.
+          'SubSystem': '2',
+          'AdditionalDependencies': [
+            'shlwapi.lib',
+          ],
         },
       },
     },
diff --git a/chrome_frame/event_hooker.cc b/chrome_frame/event_hooker.cc
new file mode 100644
index 0000000..839b3ad
--- /dev/null
+++ b/chrome_frame/event_hooker.cc
@@ -0,0 +1,58 @@
+// 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.
+
+#include "chrome_frame/event_hooker.h"
+
+#include <crtdbg.h>
+#include "chrome_frame/bho_loader.h"
+
+EXTERN_C IMAGE_DOS_HEADER __ImageBase;
+
+EventHooker::EventHooker()
+: window_creation_hook_(NULL) {}
+
+EventHooker::~EventHooker() {
+  StopHook();
+}
+
+bool EventHooker::StartHook() {
+  if ((NULL != window_creation_hook_)) {
+    return false;
+  }
+
+  window_creation_hook_ = SetWinEventHook(EVENT_OBJECT_CREATE,
+                                          EVENT_OBJECT_CREATE,
+                                          reinterpret_cast<HMODULE>(
+                                              &__ImageBase),
+                                          WindowCreationHookProc,
+                                          0,
+                                          0,
+                                          WINEVENT_INCONTEXT);
+  if (NULL == window_creation_hook_) {
+    return false;
+  }
+  return true;
+}
+
+void EventHooker::StopHook() {
+  if (NULL != window_creation_hook_) {
+    UnhookWinEvent(window_creation_hook_);
+    window_creation_hook_ = NULL;
+  }
+}
+
+VOID CALLBACK EventHooker::WindowCreationHookProc(HWINEVENTHOOK hook,
+                                                  DWORD event,
+                                                  HWND window,
+                                                  LONG object_id,
+                                                  LONG child_id,
+                                                  DWORD event_tid,
+                                                  DWORD event_time) {
+  _ASSERTE((EVENT_OBJECT_CREATE == event) ||
+           (EVENT_OBJECT_PARENTCHANGE == event));
+  if (OBJID_WINDOW == object_id) {
+    BHOLoader::GetInstance()->OnHookEvent(event, window);
+  }
+}
+
diff --git a/chrome_frame/event_hooker.h b/chrome_frame/event_hooker.h
new file mode 100644
index 0000000..1f62fbf
--- /dev/null
+++ b/chrome_frame/event_hooker.h
@@ -0,0 +1,36 @@
+// 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.
+
+#include <windows.h>
+
+#ifndef CHROME_FRAME_EVENT_HOOKER_H_
+#define CHROME_FRAME_EVENT_HOOKER_H_
+
+class EventHooker {
+ public:
+  EventHooker();
+  ~EventHooker();
+
+  // Call this to install event hooks that will trigger on window creation
+  // and reparenting. Returns true if the hooks are successfully installed,
+  // false otherwise.
+  bool StartHook();
+
+  // Call this to remove the event hooks that are installed by StartHook().
+  void StopHook();
+
+  // The callback invoked in response to an event registered for in StartHook().
+  static VOID CALLBACK WindowCreationHookProc(HWINEVENTHOOK hook,
+                                              DWORD event,
+                                              HWND window,
+                                              LONG object_id,
+                                              LONG child_id,
+                                              DWORD event_tid,
+                                              DWORD event_time);
+
+ private:
+  HWINEVENTHOOK window_creation_hook_;
+};
+
+#endif  // CHROME_FRAME_EVENT_HOOKER_H_