Fixed and reenabled the flaky test "WebViewAPITest.TestAutosizeAfterNavigation".

extensions/browser/guest_view/guest_view_base.cc

 // Copyright 2014 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 "extensions/browser/guest_view/guest_view_base.h"
 
 #include "base/lazy_instance.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/ui/zoom/page_zoom.h"
 #include "components/ui/zoom/zoom_controller.h"
@@ skipping 274 matching lines @@
 
     if (auto_size_enabled_) {
       // Autosize was previously enabled.
       rvh->DisableAutoResize(new_size);
       GuestSizeChangedDueToAutoSize(guest_size_, new_size);
     } else {
       // Autosize was already disabled.
       guest_sizer_->SizeContents(new_size);
     }
 
+    DispatchOnResizeEvent(guest_size_, new_size);
     guest_size_ = new_size;
   }
 
   auto_size_enabled_ = enable_auto_size;
 }
 
 // static
 void GuestViewBase::RegisterGuestViewType(
     const std::string& view_type,
     const GuestCreationCallback& callback) {
@@ skipping 95 matching lines @@
       element_instance_id_));
   element_instance_id_ = guestview::kInstanceIDNone;
 }
 
 void GuestViewBase::ElementSizeChanged(const gfx::Size& size) {
   if (size.IsEmpty())
     return;
 
   // Only resize if needed.
   guest_sizer_->SizeContents(size);
+  DispatchOnResizeEvent(guest_size_, size);
   guest_size_ = size;
 }
 
 WebContents* GuestViewBase::GetOwnerWebContents() const {
   return owner_web_contents_;
 }
 
-void GuestViewBase::GuestSizeChanged(const gfx::Size& old_size,
-                                     const gfx::Size& new_size) {
-  DispatchOnResizeEvent(old_size, new_size);
-
+void GuestViewBase::GuestSizeChanged(const gfx::Size& new_size) {
   if (!auto_size_enabled_)
     return;
+  GuestSizeChangedDueToAutoSize(guest_size_, new_size);
+  DispatchOnResizeEvent(guest_size_, new_size);
   guest_size_ = new_size;
-  GuestSizeChangedDueToAutoSize(old_size, new_size);
 }
 
 const GURL& GuestViewBase::GetOwnerSiteURL() const {
   return owner_web_contents()->GetLastCommittedURL();
 }
 
 void GuestViewBase::Destroy() {
   if (is_being_destroyed_)
     return;
 
@@ skipping 307 matching lines @@
 // static
 void GuestViewBase::RegisterGuestViewTypes() {
   AppViewGuest::Register();
   ExtensionOptionsGuest::Register();
   MimeHandlerViewGuest::Register();
   SurfaceWorkerGuest::Register();
   WebViewGuest::Register();
 }
 
 }  // namespace extensions