Fix for the crasher with select drop-downs

chrome/browser/renderer_host/render_widget_host_view_win.cc

 // Copyright (c) 2009 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/browser/renderer_host/render_widget_host_view_win.h"
 
 #include "app/gfx/canvas.h"
 #include "app/gfx/gdi_util.h"
 #include "app/l10n_util.h"
 #include "app/l10n_util_win.h"
@@ skipping 922 matching lines @@
     case TTN_SHOW:
       tooltip_showing_ = true;
       SetMsgHandled(TRUE);
       break;
   }
   return 0;
 }
 
 LRESULT RenderWidgetHostViewWin::OnImeSetContext(
     UINT message, WPARAM wparam, LPARAM lparam, BOOL& handled) {
+  if (!render_widget_host_)
+    return 0;
+
   // We need status messages about the focused input control from a
   // renderer process when:
   //   * the current input context has IMEs, and;
   //   * an application is activated.
   // This seems to tell we should also check if the current input context has
   // IMEs before sending a request, however, this WM_IME_SETCONTEXT is
   // fortunately sent to an application only while the input context has IMEs.
   // Therefore, we just start/stop status messages according to the activation
   // status of this application without checks.
   bool activated = (wparam == TRUE);
   if (Send(new ViewMsg_ImeSetInputMode(
       render_widget_host_->routing_id(), activated))) {
     ime_notification_ = activated;
   }
 
   if (ime_notification_)
     ime_input_.CreateImeWindow(m_hWnd);
 
   ime_input_.CleanupComposition(m_hWnd);
   ime_input_.SetImeWindowStyle(m_hWnd, message, wparam, lparam, &handled);
   return 0;
 }
 
 LRESULT RenderWidgetHostViewWin::OnImeStartComposition(
     UINT message, WPARAM wparam, LPARAM lparam, BOOL& handled) {
+  if (!render_widget_host_)
+    return 0;
+
   // Reset the composition status and create IME windows.
   ime_input_.CreateImeWindow(m_hWnd);
   ime_input_.ResetComposition(m_hWnd);
   // We have to prevent WTL from calling ::DefWindowProc() because the function
   // calls ::ImmSetCompositionWindow() and ::ImmSetCandidateWindow() to
   // over-write the position of IME windows.
   handled = TRUE;
   return 0;
 }
 
 LRESULT RenderWidgetHostViewWin::OnImeComposition(
     UINT message, WPARAM wparam, LPARAM lparam, BOOL& handled) {
+  if (!render_widget_host_)
+    return 0;
+
   // At first, update the position of the IME window.
   ime_input_.UpdateImeWindow(m_hWnd);
 
   // Retrieve the result string and its attributes of the ongoing composition
   // and send it to a renderer process.
   ImeComposition composition;
   if (ime_input_.GetResult(m_hWnd, lparam, &composition)) {
     Send(new ViewMsg_ImeSetComposition(render_widget_host_->routing_id(),
                                        WebKit::WebCompositionCommandConfirm,
                                        composition.cursor_position,
@@ skipping 17 matching lines @@
                                        composition.ime_string));
   }
   // We have to prevent WTL from calling ::DefWindowProc() because we do not
   // want for the IMM (Input Method Manager) to send WM_IME_CHAR messages.
   handled = TRUE;
   return 0;
 }
 
 LRESULT RenderWidgetHostViewWin::OnImeEndComposition(
     UINT message, WPARAM wparam, LPARAM lparam, BOOL& handled) {
+  if (!render_widget_host_)
+    return 0;
+
   if (ime_input_.is_composing()) {
     // A composition has been ended while there is an ongoing composition,
     // i.e. the ongoing composition has been canceled.
     // We need to reset the composition status both of the ImeInput object and
     // of the renderer process.
     std::wstring empty_string;
     Send(new ViewMsg_ImeSetComposition(render_widget_host_->routing_id(),
                                        WebKit::WebCompositionCommandDiscard,
                                        -1, -1, -1, empty_string));
     ime_input_.ResetComposition(m_hWnd);
@@ skipping 361 matching lines @@
     SetFocus();
   }
 }
 
 void RenderWidgetHostViewWin::ShutdownHost() {
   shutdown_factory_.RevokeAll();
   if (render_widget_host_)
     render_widget_host_->Shutdown();
   // Do not touch any members at this point, |this| has been deleted.
 }