Android: Don't destroy LayerTreeHost when Surface goes away

chrome/browser/android/thumbnail/thumbnail_cache.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 "chrome/browser/android/thumbnail/thumbnail_cache.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/android/path_utils.h"
@@ skipping 455 matching lines @@
     cache_.Remove(key_to_remove);
 }
 
 void ThumbnailCache::RemoveFromReadQueue(TabId tab_id) {
   TabIdList::iterator read_iter =
       std::find(read_queue_.begin(), read_queue_.end(), tab_id);
   if (read_iter != read_queue_.end())
     read_queue_.erase(read_iter);
 }
 
+void ThumbnailCache::OnUIResourcesWereEvicted() {
+  cache_.Clear();
+  approximation_cache_.Clear();
+}
+
 void ThumbnailCache::InvalidateCachedThumbnail(Thumbnail* thumbnail) {
   DCHECK(thumbnail);
   TabId tab_id = thumbnail->tab_id();
   cc::UIResourceId uid = thumbnail->ui_resource_id();
 
   Thumbnail* cached_thumbnail = cache_.Get(tab_id);
   if (cached_thumbnail && cached_thumbnail->ui_resource_id() == uid)
     cache_.Remove(tab_id);
 
   cached_thumbnail = approximation_cache_.Get(tab_id);
@@ skipping 438 matching lines @@
   dst_bitmap.eraseColor(0);
   SkAutoLockPixels dst_bitmap_lock(dst_bitmap);
 
   SkCanvas canvas(dst_bitmap);
   canvas.scale(new_scale, new_scale);
   canvas.drawBitmap(bitmap, 0, 0, NULL);
   dst_bitmap.setImmutable();
 
   return std::make_pair(dst_bitmap, new_scale * scale);
 }