[content] Do not unnecessarily handle delegated_frame_host_ being null in RenderWidgetHostViewAura.

This is a cleanup prior to fixing crbug.com/1164477. It improves
readability by removing code that handles situations that never occur.

Bug: 1164477
Change-Id: I3251051a3f66283853bf551c29284595621bd759
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2616354
Commit-Queue: Charlie Reis <creis@chromium.org>
Auto-Submit: François Doray <fdoray@chromium.org>
Reviewed-by: Charlie Reis <creis@chromium.org>
Reviewed-by: danakj <danakj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843677}

content/browser/renderer_host/render_widget_host_view_aura.cc

@@ -534,8 +534,7 @@ bool RenderWidgetHostViewAura::HasFocus() {
 }
 
 bool RenderWidgetHostViewAura::IsSurfaceAvailableForCopy() {
-  if (!delegated_frame_host_)
-    return false;
+  DCHECK(delegated_frame_host_) << "Cannot be invoked during destruction.";
   return delegated_frame_host_->CanCopyFromCompositingSurface();
 }
 
@@ -550,6 +549,8 @@ bool RenderWidgetHostViewAura::IsShowing() {
 }
 
 void RenderWidgetHostViewAura::WasUnOccluded() {
+  DCHECK(delegated_frame_host_) << "Cannot be invoked during destruction.";
+
   const Visibility old_visibility = visibility_;
   visibility_ = Visibility::VISIBLE;
 
@@ -565,8 +566,7 @@ void RenderWidgetHostViewAura::WasUnOccluded() {
   }
 
   auto tab_switch_start_state = TakeRecordContentToVisibleTimeRequest();
-  bool has_saved_frame =
-      delegated_frame_host_ ? delegated_frame_host_->HasSavedFrame() : false;
+  bool has_saved_frame = delegated_frame_host_->HasSavedFrame();
 
   bool show_reason_bfcache_restore =
       tab_switch_start_state
@@ -589,14 +589,12 @@ void RenderWidgetHostViewAura::WasUnOccluded() {
       NotifyRendererOfCursorVisibilityState(cursor_client->IsCursorVisible());
   }
 
-  if (delegated_frame_host_) {
-    // If the frame for the renderer is already available, then the
-    // tab-switching time is the presentation time for the browser-compositor.
-    delegated_frame_host_->WasShown(
-        GetLocalSurfaceId(), window_->bounds().size(),
-        has_saved_frame ? std::move(tab_switch_start_state)
-                        : blink::mojom::RecordContentToVisibleTimeRequestPtr());
-  }
+  // If the frame for the renderer is already available, then the
+  // tab-switching time is the presentation time for the browser-compositor.
+  delegated_frame_host_->WasShown(
+      GetLocalSurfaceId(), window_->bounds().size(),
+      has_saved_frame ? std::move(tab_switch_start_state)
+                      : blink::mojom::RecordContentToVisibleTimeRequestPtr());
 
 #if defined(OS_WIN)
   UpdateLegacyWin();
@@ -604,13 +602,13 @@ void RenderWidgetHostViewAura::WasUnOccluded() {
 }
 
 void RenderWidgetHostViewAura::HideImpl() {
+  DCHECK(delegated_frame_host_) << "Cannot be invoked during destruction.";
   DCHECK(visibility_ == Visibility::HIDDEN ||
          visibility_ == Visibility::OCCLUDED);
 
   if (!host()->is_hidden()) {
     host()->WasHidden();
     aura::WindowTreeHost* host = window_->GetHost();
-    if (delegated_frame_host_) {
       aura::Window* parent = window_->parent();
       aura::Window::OcclusionState parent_occl_state =
           parent ? parent->occlusion_state()
@@ -627,7 +625,6 @@ void RenderWidgetHostViewAura::HideImpl() {
         cause = DelegatedFrameHost::HiddenCause::kOther;
       }
       delegated_frame_host_->WasHidden(cause);
-    }
 #if defined(OS_WIN)
     if (host) {
       // We reparent the legacy Chrome_RenderWidgetHostHWND window to the global
@@ -679,10 +676,9 @@ void RenderWidgetHostViewAura::SetDisplayFeatureForTesting(
 }
 
 void RenderWidgetHostViewAura::WindowTitleChanged() {
-  if (delegated_frame_host_) {
-    delegated_frame_host_->WindowTitleChanged(
-        base::UTF16ToUTF8(window_->GetTitle()));
-  }
+  DCHECK(delegated_frame_host_) << "Cannot be invoked during destruction.";
+  delegated_frame_host_->WindowTitleChanged(
+      base::UTF16ToUTF8(window_->GetTitle()));
 }
 
 bool RenderWidgetHostViewAura::IsMouseLocked() {
@@ -824,8 +820,8 @@ RenderWidgetHostViewAura::GetParentNativeViewAccessible() {
 }
 
 void RenderWidgetHostViewAura::ResetFallbackToFirstNavigationSurface() {
-  if (delegated_frame_host_)
-    delegated_frame_host_->ResetFallbackToFirstNavigationSurface();
+  DCHECK(delegated_frame_host_) << "Cannot be invoked during destruction.";
+  delegated_frame_host_->ResetFallbackToFirstNavigationSurface();
 }
 
 bool RenderWidgetHostViewAura::RequestRepaintForTesting() {
@@ -1762,14 +1758,17 @@ void RenderWidgetHostViewAura::OnMouseEvent(ui::MouseEvent* event) {
 }
 
 bool RenderWidgetHostViewAura::HasFallbackSurface() const {
-  return delegated_frame_host_ && delegated_frame_host_->HasFallbackSurface();
+  DCHECK(delegated_frame_host_) << "Cannot be invoked during destruction.";
+  return delegated_frame_host_->HasFallbackSurface();
 }
 
 bool RenderWidgetHostViewAura::TransformPointToCoordSpaceForView(
     const gfx::PointF& point,
     RenderWidgetHostViewBase* target_view,
     gfx::PointF* transformed_point) {
-  if (target_view == this || !delegated_frame_host_) {
+  DCHECK(delegated_frame_host_) << "Cannot be invoked during destruction.";
+
+  if (target_view == this) {
     *transformed_point = point;
     return true;
   }
@@ -1789,8 +1788,8 @@ viz::FrameSinkId RenderWidgetHostViewAura::GetRootFrameSinkId() {
 }
 
 viz::SurfaceId RenderWidgetHostViewAura::GetCurrentSurfaceId() const {
-  return delegated_frame_host_ ? delegated_frame_host_->GetCurrentSurfaceId()
-                               : viz::SurfaceId();
+  DCHECK(delegated_frame_host_) << "Cannot be invoked during destruction.";
+  return delegated_frame_host_->GetCurrentSurfaceId();
 }
 
 void RenderWidgetHostViewAura::FocusedNodeChanged(
@@ -2105,16 +2104,17 @@ bool RenderWidgetHostViewAura::SynchronizeVisualProperties(
     const cc::DeadlinePolicy& deadline_policy,
     const base::Optional<viz::LocalSurfaceId>& child_local_surface_id) {
   DCHECK(window_);
+  DCHECK(delegated_frame_host_) << "Cannot be invoked during destruction.";
+
   window_->UpdateLocalSurfaceIdFromEmbeddedClient(child_local_surface_id);
   // If the viz::LocalSurfaceId is invalid, we may have been evicted,
   // allocate a new one to establish bounds.
   if (!GetLocalSurfaceId().is_valid())
     window_->AllocateLocalSurfaceId();
 
-  if (delegated_frame_host_) {
-    delegated_frame_host_->EmbedSurface(
-        GetLocalSurfaceId(), window_->bounds().size(), deadline_policy);
-  }
+  delegated_frame_host_->EmbedSurface(
+      GetLocalSurfaceId(), window_->bounds().size(), deadline_policy);
+
   return host()->SynchronizeVisualProperties();
 }
 
@@ -2289,6 +2289,8 @@ void RenderWidgetHostViewAura::UpdateLegacyWin() {
 #endif
 
 void RenderWidgetHostViewAura::AddedToRootWindow() {
+  DCHECK(delegated_frame_host_) << "Cannot be invoked during destruction.";
+
   window_->GetHost()->AddObserver(this);
   UpdateScreenInfo(window_);
 
@@ -2308,11 +2310,12 @@ void RenderWidgetHostViewAura::AddedToRootWindow() {
   UpdateLegacyWin();
 #endif
 
-  if (delegated_frame_host_)
     delegated_frame_host_->AttachToCompositor(window_->GetHost()->compositor());
 }
 
 void RenderWidgetHostViewAura::RemovingFromRootWindow() {
+  DCHECK(delegated_frame_host_) << "Cannot be invoked during destruction.";
+
   aura::client::CursorClient* cursor_client =
       aura::client::GetCursorClient(window_->GetRootWindow());
   if (cursor_client)
@@ -2321,7 +2324,6 @@ void RenderWidgetHostViewAura::RemovingFromRootWindow() {
   DetachFromInputMethod(true);
 
   window_->GetHost()->RemoveObserver(this);
-  if (delegated_frame_host_)
     delegated_frame_host_->DetachFromCompositor();
 
 #if defined(OS_WIN)
@@ -2406,9 +2408,10 @@ void RenderWidgetHostViewAura::CreateSelectionController() {
 }
 
 void RenderWidgetHostViewAura::OnDidNavigateMainFrameToNewPage() {
+  DCHECK(delegated_frame_host_) << "Cannot be invoked during destruction.";
+
   // Invalidate the surface so that we don't attempt to evict it multiple times.
   window_->InvalidateLocalSurfaceId();
-  if (delegated_frame_host_)
     delegated_frame_host_->OnNavigateToNewPage();
   CancelActiveTouches();
 }
@@ -2566,6 +2569,8 @@ RenderWidgetHostViewAura::DidUpdateVisualProperties(
 }
 
 void RenderWidgetHostViewAura::DidNavigate() {
+  DCHECK(delegated_frame_host_) << "Cannot be invoked during destruction.";
+
   if (!IsShowing()) {
     // Navigating while hidden should not allocate a new LocalSurfaceID. Once
     // sizes are ready, or we begin to Show, we can then allocate the new
@@ -2582,7 +2587,6 @@ void RenderWidgetHostViewAura::DidNavigate() {
                                   base::nullopt);
     }
   }
-  if (delegated_frame_host_)
     delegated_frame_host_->DidNavigate();
   is_first_navigation_ = false;
 }
@@ -2601,10 +2605,10 @@ void RenderWidgetHostViewAura::TakeFallbackContentFrom(
   if (color)
     SetBackgroundColor(*color);
 
-  if (delegated_frame_host_ && view_aura->delegated_frame_host_) {
-    delegated_frame_host_->TakeFallbackContentFrom(
-        view_aura->delegated_frame_host_.get());
-  }
+  DCHECK(delegated_frame_host_) << "Cannot be invoked during destruction.";
+  DCHECK(view_aura->delegated_frame_host_);
+  delegated_frame_host_->TakeFallbackContentFrom(
+      view_aura->delegated_frame_host_.get());
   host()->GetContentRenderingTimeoutFrom(view_aura->host());
 }
 

content/browser/renderer_host/render_widget_host_view_aura.h

@@ -592,7 +592,7 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
   aura::Window* window_;
 
   std::unique_ptr<DelegatedFrameHostClient> delegated_frame_host_client_;
-  // NOTE: this may be null.
+  // NOTE: this may be null during destruction.
   std::unique_ptr<DelegatedFrameHost> delegated_frame_host_;
 
   std::unique_ptr<WindowObserver> window_observer_;