Fix the issue that any tab/window closing hotkey will crash the Pepper Flash Fullscreen.

content/browser/renderer_host/render_widget_host_impl.cc

Index: content/browser/renderer_host/render_widget_host_impl.cc
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index d4e2e53fd5904e0d9a63ef0e59372f23a38b3b8a..3e636154e2fedb3bf7bac4c886fc1ea41fbb6e5c 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -185,6 +185,9 @@ RenderWidgetHostImpl::~RenderWidgetHostImpl() {
   surface_id_ = 0;
 
   process_->Release(routing_id_);
+
+  if (delegate_)
+    delegate_->RenderWidgetDeleted(this);
 }
 
 // static
@@ -963,10 +966,6 @@ void RenderWidgetHostImpl::ForwardKeyboardEvent(
 
     bool is_keyboard_shortcut = false;
     // Only pre-handle the key event if it's not handled by the input method.
-    // A delegate_ of NULL seems impossible but crash reports show that it
-    // can happen (see http://crbug.com/134465). This doesn't seem to happen
-    // with Chrome 22 and later, so checking the delegate_ here can be removed
-    // once Chrome 22 goes to stable..
     if (delegate_ && !key_event.skip_in_browser) {
       // We need to set |suppress_next_char_events_| to true if
       // PreHandleKeyboardEvent() returns true, but |this| may already be
@@ -1846,7 +1845,7 @@ void RenderWidgetHostImpl::ProcessKeyboardEventAck(int type, bool processed) {
     // We only send unprocessed key event upwards if we are not hidden,
     // because the user has moved away from us and no longer expect any effect
     // of this key event.
-    if (!processed && !is_hidden_ && !front_item.skip_in_browser) {
+    if (delegate_ && !processed && !is_hidden_ && !front_item.skip_in_browser) {
       delegate_->HandleKeyboardEvent(front_item);
 
       // WARNING: This RenderWidgetHostImpl can be deallocated at this point
@@ -2057,4 +2056,8 @@ void RenderWidgetHostImpl::DelayedAutoResized() {
   OnRenderAutoResized(new_size);
 }
 
+void RenderWidgetHostImpl::DetachDelegate() {
+  delegate_ = NULL;
+}
+
 }  // namespace content