Remove SelfKeepAlive from WebFrameWidgetImpl.

WebFrameWidgetImpl is a GC'd object and owned by the WebLocalFrameImpl
exclusively, it does not need a SelfKeepAlive reference.

BUG=1097816

Change-Id: Ic6c6ec91214e7ab51e879d6aa6fdbe56d06954e1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2571421
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#835700}

third_party/blink/renderer/core/frame/web_frame_widget_impl.cc

@@ -245,8 +245,7 @@ WebFrameWidgetImpl::WebFrameWidgetImpl(
                                                 never_composited,
                                                 is_for_child_local_root)),
       frame_sink_id_(frame_sink_id),
-      is_for_child_local_root_(is_for_child_local_root),
-      self_keep_alive_(PERSISTENT_FROM_HERE, this) {
+      is_for_child_local_root_(is_for_child_local_root) {
   DCHECK(task_runner);
   if (is_for_nested_main_frame)
     main_data().is_for_nested_main_frame = is_for_nested_main_frame;
@@ -303,7 +302,6 @@ void WebFrameWidgetImpl::Close() {
   input_handler_weak_ptr_factory_.InvalidateWeakPtrs();
   receiver_.reset();
   input_target_receiver_.reset();
-  self_keep_alive_.Clear();
 }
 
 WebLocalFrame* WebFrameWidgetImpl::LocalRoot() const {

third_party/blink/renderer/core/frame/web_frame_widget_impl.h

@@ -1026,8 +1026,6 @@ class CORE_EXPORT WebFrameWidgetImpl
   // closed.
   scoped_refptr<WebPagePopupImpl> last_hidden_page_popup_;
 
-  SelfKeepAlive<WebFrameWidgetImpl> self_keep_alive_;
-
   base::WeakPtrFactory<mojom::blink::FrameWidgetInputHandler>
       input_handler_weak_ptr_factory_{this};
 };