Android: Don't destroy LayerTreeHost when Surface goes away

chrome/browser/android/thumbnail/thumbnail.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 "base/logging.h"
 #include "chrome/browser/android/thumbnail/thumbnail.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "ui/android/resources/ui_resource_provider.h"
 #include "ui/gfx/geometry/size_conversions.h"
@@ skipping 37 matching lines @@
       thumbnail_delegate_(thumbnail_delegate) {
 }
 
 Thumbnail::~Thumbnail() {
   ClearUIResourceId();
 }
 
 void Thumbnail::SetBitmap(const SkBitmap& bitmap) {
   DCHECK(!bitmap.empty());
   retrieved_ = false;
+  // TODO(sievers): We really just need to invalidate it here.
   ClearUIResourceId();
   scaled_content_size_ =
       gfx::ScaleSize(gfx::Size(bitmap.width(), bitmap.height()), 1.f / scale_);
   scaled_data_size_ = scaled_content_size_;
   bitmap_ = cc::UIResourceBitmap(bitmap);
 }
 
 void Thumbnail::SetCompressedBitmap(skia::RefPtr<SkPixelRef> compressed_bitmap,
                                     const gfx::Size& content_size) {
   DCHECK(compressed_bitmap);
   DCHECK(!content_size.IsEmpty());
   retrieved_ = false;
+  // TODO(sievers): We really just need to invalidate it here.
   ClearUIResourceId();
   gfx::Size data_size(compressed_bitmap->info().width(),
                       compressed_bitmap->info().height());
   scaled_content_size_ = gfx::ScaleSize(content_size, 1.f / scale_);
   scaled_data_size_ = gfx::ScaleSize(data_size, 1.f / scale_);
   bitmap_ = cc::UIResourceBitmap(compressed_bitmap, data_size);
 }
 
 void Thumbnail::CreateUIResource() {
   DCHECK(ui_resource_provider_);
   if (!ui_resource_id_)
     ui_resource_id_ = ui_resource_provider_->CreateUIResource(this);
 }
 
 cc::UIResourceBitmap Thumbnail::GetBitmap(cc::UIResourceId uid,
                                           bool resource_lost) {
   if (retrieved_)
     return bitmap_;
 
   retrieved_ = true;
 
   cc::UIResourceBitmap old_bitmap(bitmap_);
   // Return a place holder for all other calls to GetBitmap.

[no sievers, 2015/09/24 23:27:43]

This is basically what is making it hard to simplify the UI resource management
further without making other changes.

The invalidation below also actually causes it to delete |this|, so this needs a
bite more rework.

   bitmap_ = cc::UIResourceBitmap(CreateSmallHolderBitmap());
   return old_bitmap;
 }
 
-void Thumbnail::UIResourceIsInvalid() {
-  ui_resource_id_ = 0;
+void Thumbnail::OnWasEvicted() {
   if (thumbnail_delegate_)
     thumbnail_delegate_->InvalidateCachedThumbnail(this);
 }
 
 void Thumbnail::ClearUIResourceId() {
   if (ui_resource_id_ && ui_resource_provider_)
     ui_resource_provider_->DeleteUIResource(ui_resource_id_);
   ui_resource_id_ = 0;
 }