Revert "Synchronize NavigableContentsView's LocalHostView focus w/ window focus."

This reverts commit 22c7b0a0.

Reason for revert: Causing b/140266795.

Original change's description:
> Synchronize NavigableContentsView's LocalHostView focus w/ window focus.
>
> Previously, if the user clicked into the WebContents of an
> AssistantCardElementView, the corresponding RenderWidgetHostViewAura
> would become focused. However, the focused view in the Assistant view
> hierarchy (usually the Textfield in the Assistant Dialog Plate) wouldn't
> receive a blur event. As such, the user would think they could keep
> typing because of the blinking caret in the Textfield. When typing,
> they would find nothing entered and think keyboard was broken.
>
> Now, we synchronize the focus state of NavigableContentsView's
> LocalHostView with the associated native window so that as the native
> window subtree takes focus, so does the LocalHostView.
>
> This fixes AssistantCardElementView further upstream.
>
> Bug: b:134170714
> Change-Id: I03d67a3d9fbc779a87449065c97d7e4a877fe10a
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1649084
> Commit-Queue: David Black <dmblack@google.com>
> Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
> Reviewed-by: Ken Rockot <rockot@google.com>
> Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#668077}

TBR=xiyuan@chromium.org,rockot@google.com,xiaohuic@chromium.org,dmblack@google.com,wutao@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: b:134170714, b:140266795
Change-Id: I4de99b2ef2c18bb503277fc4a528866b2c832764
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1778989Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Reviewed-by: Tao Wu <wutao@chromium.org>
Commit-Queue: David Black <dmblack@google.com>
Cr-Commit-Position: refs/heads/master@{#692866}

ash/app_list/views/search_result_answer_card_view.cc

@@ -262,10 +262,6 @@ class SearchResultAnswerCardView::AnswerCardResultView
     OnVisibilityChanged(true /* is_visible */);
     views::View* content_view = contents_->GetView()->view();
     if (children().empty()) {
-      // Focusability is handled on SearchResultAnswerCardView so we explicitly
-      // disable it on the embedded view (for which it is enabled by default).
-      content_view->SetFocusBehavior(FocusBehavior::NEVER);
-
       AddChildView(content_view);
       ExcludeCardFromEventHandling(contents_->GetView()->native_view());
 

services/content/public/cpp/navigable_contents_view.cc

@@ -22,8 +22,6 @@
 #endif  // defined(TOOLKIT_VIEWS)
 
 #if defined(USE_AURA)
-#include "ui/aura/client/focus_change_observer.h"  // nogncheck
-#include "ui/aura/client/focus_client.h"           // nogncheck
 #include "ui/aura/layout_manager.h"  // nogncheck
 #include "ui/aura/window.h"          // nogncheck
 #endif
@@ -77,25 +75,14 @@ class LocalWindowLayoutManager : public aura::LayoutManager {
 
 // Owns an Aura window which parents another Aura window in the same process,
 // corresponding to a web contents view hosted in the process.
-class LocalViewHost : public views::NativeViewHost,
-                      public aura::WindowObserver,
-                      public aura::client::FocusChangeObserver {
+class LocalViewHost : public views::NativeViewHost {
  public:
   LocalViewHost(aura::Window* window, NavigableContents* contents)
       : window_(window), contents_(contents) {
     window_->SetLayoutManager(new LocalWindowLayoutManager(window_));
-    window_->AddObserver(this);
-
-    // We set focus behavior to |ALWAYS| to ensure that we receive window focus
-    // change events when our hosted WebContents takes focus. We utilize this
-    // change event to keep LocalViewHost and WebContents focus state in sync.
-    SetFocusBehavior(FocusBehavior::ALWAYS);
   }
 
-  ~LocalViewHost() override {
-    if (!window_destroyed_)
-      window_->RemoveObserver(this);
-  }
+  ~LocalViewHost() override = default;
 
   // views::View:
   void AddedToWidget() override {
@@ -116,54 +103,10 @@ class LocalViewHost : public views::NativeViewHost,
     }
   }
 
-  // aura::WindowObserver:
-  void OnWindowAddedToRootWindow(aura::Window* window) override {
-    // Once our |window_| has been added to its root window, we can obtain a
-    // reference to the root window's focus client which we observe to detect
-    // window focus changed events.
-    auto* focus_client = aura::client::GetFocusClient(window_);
-    if (focus_client)
-      focus_client->AddObserver(this);
-  }
-
-  void OnWindowRemovingFromRootWindow(aura::Window* window,
-                                      aura::Window* root_window) override {
-    // We need to stop observing the root window's focus client before our
-    // |window_| is removed. Otherwise, we will leak a pointer to LocalViewHost
-    // to the focus client that will persist even after LocalViewHost is
-    // destroyed. This will cause a crash when the focus client attempts to
-    // notify our destroyed instance of focus changed events.
-    auto* focus_client = aura::client::GetFocusClient(window_);
-    if (focus_client)
-      focus_client->RemoveObserver(this);
-  }
-
-  void OnWindowDestroying(aura::Window* window) override {
-    window_->RemoveObserver(this);
-    window_destroyed_ = true;
-  }
-
-  // aura::client::FocusChangeObserver:
-  void OnWindowFocused(aura::Window* gained_focus,
-                       aura::Window* lost_focus) override {
-    // We need to ensure that LocalViewHost's focus state is synced with that of
-    // |window_|. This only needs to be done when gaining focus and when
-    // LocalViewHost doesn't already have focus.
-    if (!gained_focus || HasFocus())
-      return;
-
-    // When the window gaining focus is contained within |window_|, we need to
-    // request focus on LocalHostView to remain in sync.
-    if (window_->Contains(gained_focus))
-      RequestFocus();
-  }
-
  private:
   aura::Window* const window_;
   NavigableContents* const contents_;
 
-  bool window_destroyed_ = false;
-
   DISALLOW_COPY_AND_ASSIGN(LocalViewHost);
 };