Merge 210713 "cc: Remove tile ref counting in tile manager."

cc/resources/tile_manager.cc

 // Copyright 2012 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 "cc/resources/tile_manager.h"
 
 #include <algorithm>
 #include <limits>
 #include <string>
 
@@ skipping 71 matching lines @@
     TileManagerClient* client,
     ResourceProvider* resource_provider,
     scoped_ptr<RasterWorkerPool> raster_worker_pool,
     size_t num_raster_threads,
     bool use_color_estimator,
     RenderingStatsInstrumentation* rendering_stats_instrumentation,
     GLenum texture_format)
     : client_(client),
       resource_pool_(ResourcePool::Create(resource_provider)),
       raster_worker_pool_(raster_worker_pool.Pass()),
+      all_tiles_required_for_activation_have_been_initialized_(true),
+      all_tiles_required_for_activation_have_memory_(true),
       ever_exceeded_memory_budget_(false),
       rendering_stats_instrumentation_(rendering_stats_instrumentation),
       use_color_estimator_(use_color_estimator),
       did_initialize_visible_tile_(false),
       texture_format_(texture_format) {
   raster_worker_pool_->SetClient(this);
 }
 
 TileManager::~TileManager() {
   // Reset global state and manage. This should cause
   // our memory usage to drop to zero.
   global_state_ = GlobalStateThatImpactsTilePriority();
-  AssignGpuMemoryToTiles();
-  CleanUpUnusedImageDecodeTasks();
+
+  // Clear |sorted_tiles_| so that tiles kept alive by it can be freed.
+  sorted_tiles_.clear();
+  DCHECK_EQ(0u, tiles_.size());
+
+  TileVector empty;
+  ScheduleTasks(empty);
+
   // This should finish all pending tasks and release any uninitialized
   // resources.
   raster_worker_pool_->Shutdown();
   raster_worker_pool_->CheckForCompletedTasks();
-  DCHECK_EQ(0u, tiles_.size());
 }
 
 void TileManager::SetGlobalState(
     const GlobalStateThatImpactsTilePriority& global_state) {
   global_state_ = global_state;
   resource_pool_->SetMaxMemoryUsageBytes(
       global_state_.memory_limit_in_bytes,
       global_state_.unused_memory_limit_in_bytes);
 }
 
 void TileManager::RegisterTile(Tile* tile) {
-  DCHECK(std::find(tiles_.begin(), tiles_.end(), tile) == tiles_.end());
   DCHECK(!tile->required_for_activation());
-  tiles_.push_back(tile);
+  DCHECK(tiles_.find(tile->id()) == tiles_.end());
+
+  tiles_[tile->id()] = tile;
 }
 
 void TileManager::UnregisterTile(Tile* tile) {
-  TileVector::iterator raster_iter =
-      std::find(tiles_that_need_to_be_rasterized_.begin(),
-                tiles_that_need_to_be_rasterized_.end(),
-                tile);
-  if (raster_iter != tiles_that_need_to_be_rasterized_.end())
-    tiles_that_need_to_be_rasterized_.erase(raster_iter);
+  FreeResourcesForTile(tile);
 
-  tiles_that_need_to_be_initialized_for_activation_.erase(tile);
-  oom_tiles_that_need_to_be_initialized_for_activation_.erase(tile);
-
-  DCHECK(std::find(tiles_.begin(), tiles_.end(), tile) != tiles_.end());
-  FreeResourcesForTile(tile);
-  tiles_.erase(std::remove(tiles_.begin(), tiles_.end(), tile));
+  DCHECK(tiles_.find(tile->id()) != tiles_.end());
+  tiles_.erase(tile->id());
 }
 
 bool TileManager::ShouldForceTasksRequiredForActivationToComplete() const {
   return GlobalState().tree_priority != SMOOTHNESS_TAKES_PRIORITY;
 }
 
 void TileManager::DidFinishedRunningTasks() {
+  TRACE_EVENT0("cc", "TileManager::DidFinishedRunningTasks");
+
   // When OOM, keep re-assigning memory until we reach a steady state
   // where top-priority tiles are initialized.
   if (!memory_stats_from_last_assign_.bytes_over)
     return;
 
   raster_worker_pool_->CheckForCompletedTasks();
 
-  AssignGpuMemoryToTiles();
+  TileVector tiles_that_need_to_be_rasterized;
+  TileSet oom_tiles_required_for_activation;
+  AssignGpuMemoryToTiles(sorted_tiles_,
+                         &tiles_that_need_to_be_rasterized,
+                         &oom_tiles_required_for_activation);
 
-  if (!oom_tiles_that_need_to_be_initialized_for_activation_.empty())
-    ReassignGpuMemoryToOOMTilesRequiredForActivation();
+  if (!oom_tiles_required_for_activation.empty()) {
+    ReassignGpuMemoryToOOMTilesRequiredForActivation(
+        sorted_tiles_,
+        &tiles_that_need_to_be_rasterized,
+        &oom_tiles_required_for_activation);
+  }
+  all_tiles_required_for_activation_have_memory_ =
+      oom_tiles_required_for_activation.empty();
 
-  // |tiles_that_need_to_be_rasterized_| will be empty when we reach a
+  // |tiles_that_need_to_be_rasterized| will be empty when we reach a
   // steady memory state. Keep scheduling tasks until we reach this state.
-  if (!tiles_that_need_to_be_rasterized_.empty()) {
-    ScheduleTasks();
+  if (!tiles_that_need_to_be_rasterized.empty()) {
+    ScheduleTasks(tiles_that_need_to_be_rasterized);
     return;
   }
 
   // Use on-demand raster for any tiles that have not been been assigned
   // memory after reaching a steady memory state.
-  for (TileSet::iterator it =
-           oom_tiles_that_need_to_be_initialized_for_activation_.begin();
-       it != oom_tiles_that_need_to_be_initialized_for_activation_.end();
+  for (TileSet::iterator it = oom_tiles_required_for_activation.begin();
+       it != oom_tiles_required_for_activation.end();
        ++it) {
     Tile* tile = *it;
     ManagedTileState& mts = tile->managed_state();
     mts.tile_versions[mts.raster_mode].set_rasterize_on_demand();
   }
-  oom_tiles_that_need_to_be_initialized_for_activation_.clear();
 
-  DCHECK_EQ(0u, tiles_that_need_to_be_initialized_for_activation_.size());
+  DCHECK(all_tiles_required_for_activation_have_been_initialized_);
   client_->NotifyReadyToActivate();
 }
 
 void TileManager::DidFinishedRunningTasksRequiredForActivation() {
   // This is only a true indication that all tiles required for
   // activation are initialized when no tiles are OOM. We need to
   // wait for DidFinishRunningTasks() to be called, try to re-assign
   // memory and in worst case use on-demand raster when tiles
   // required for activation are OOM.
-  if (!oom_tiles_that_need_to_be_initialized_for_activation_.empty())
+  if (!all_tiles_required_for_activation_have_memory_)
     return;
 
   client_->NotifyReadyToActivate();
 }
 
 class BinComparator {
  public:
-  bool operator() (const Tile* a, const Tile* b) const {
+  bool operator()(const scoped_refptr<Tile> a,
+                  const scoped_refptr<Tile> b) const {
     const ManagedTileState& ams = a->managed_state();
     const ManagedTileState& bms = b->managed_state();
     if (ams.bin[HIGH_PRIORITY_BIN] != bms.bin[HIGH_PRIORITY_BIN])
       return ams.bin[HIGH_PRIORITY_BIN] < bms.bin[HIGH_PRIORITY_BIN];
 
     if (ams.bin[LOW_PRIORITY_BIN] != bms.bin[LOW_PRIORITY_BIN])
       return ams.bin[LOW_PRIORITY_BIN] < bms.bin[LOW_PRIORITY_BIN];
 
     if (ams.required_for_activation != bms.required_for_activation)
       return ams.required_for_activation;
@@ skipping 11 matching lines @@
     }
 
     gfx::Rect a_rect = a->content_rect();
     gfx::Rect b_rect = b->content_rect();
     if (a_rect.y() != b_rect.y())
       return a_rect.y() < b_rect.y();
     return a_rect.x() < b_rect.x();
   }
 };
 
-void TileManager::AssignBinsToTiles() {
+void TileManager::AssignBinsToTiles(TileRefVector* tiles) {
   const TreePriority tree_priority = global_state_.tree_priority;
 
   // Memory limit policy works by mapping some bin states to the NEVER bin.
   ManagedTileBin bin_map[NUM_BINS];
   if (global_state_.memory_limit_policy == ALLOW_NOTHING) {
     bin_map[NOW_BIN] = NEVER_BIN;
     bin_map[SOON_BIN] = NEVER_BIN;
     bin_map[EVENTUALLY_BIN] = NEVER_BIN;
     bin_map[NEVER_BIN] = NEVER_BIN;
   } else if (global_state_.memory_limit_policy == ALLOW_ABSOLUTE_MINIMUM) {
     bin_map[NOW_BIN] = NOW_BIN;
     bin_map[SOON_BIN] = NEVER_BIN;
     bin_map[EVENTUALLY_BIN] = NEVER_BIN;
     bin_map[NEVER_BIN] = NEVER_BIN;
   } else if (global_state_.memory_limit_policy == ALLOW_PREPAINT_ONLY) {
     bin_map[NOW_BIN] = NOW_BIN;
     bin_map[SOON_BIN] = SOON_BIN;
     bin_map[EVENTUALLY_BIN] = NEVER_BIN;
     bin_map[NEVER_BIN] = NEVER_BIN;
   } else {
     bin_map[NOW_BIN] = NOW_BIN;
     bin_map[SOON_BIN] = SOON_BIN;
     bin_map[EVENTUALLY_BIN] = EVENTUALLY_BIN;
     bin_map[NEVER_BIN] = NEVER_BIN;
   }
 
   // For each tree, bin into different categories of tiles.
-  for (TileVector::iterator it = tiles_.begin();
-       it != tiles_.end();
-       ++it) {
-    Tile* tile = *it;
+  for (TileRefVector::iterator it = tiles->begin(); it != tiles->end(); ++it) {
+    Tile* tile = it->get();
     ManagedTileState& mts = tile->managed_state();
 
     TilePriority prio[NUM_BIN_PRIORITIES];
     switch (tree_priority) {
       case SAME_PRIORITY_FOR_BOTH_TREES:
         prio[HIGH_PRIORITY_BIN] = prio[LOW_PRIORITY_BIN] =
             tile->combined_priority();
         break;
       case SMOOTHNESS_TAKES_PRIORITY:
         prio[HIGH_PRIORITY_BIN] = tile->priority(ACTIVE_TREE);
@@ skipping 12 matching lines @@
         prio[HIGH_PRIORITY_BIN].distance_to_visible_in_pixels;
     mts.required_for_activation =
         prio[HIGH_PRIORITY_BIN].required_for_activation;
     mts.bin[HIGH_PRIORITY_BIN] =
         BinFromTilePriority(prio[HIGH_PRIORITY_BIN], tree_priority);
     mts.bin[LOW_PRIORITY_BIN] =
         BinFromTilePriority(prio[LOW_PRIORITY_BIN], tree_priority);
     mts.gpu_memmgr_stats_bin =
         BinFromTilePriority(tile->combined_priority(), tree_priority);
 
-    DidTileTreeBinChange(tile,
-                         bin_map[BinFromTilePriority(
-                             tile->priority(ACTIVE_TREE), tree_priority)],
-                         ACTIVE_TREE);
-    DidTileTreeBinChange(tile,
-                         bin_map[BinFromTilePriority(
-                             tile->priority(PENDING_TREE), tree_priority)],
-                         PENDING_TREE);
+    mts.tree_bin[ACTIVE_TREE] = bin_map[
+        BinFromTilePriority(tile->priority(ACTIVE_TREE), tree_priority)];
+    mts.tree_bin[PENDING_TREE] = bin_map[
+        BinFromTilePriority(tile->priority(PENDING_TREE), tree_priority)];
 
     for (int i = 0; i < NUM_BIN_PRIORITIES; ++i)
       mts.bin[i] = bin_map[mts.bin[i]];
   }
 }
 
-void TileManager::SortTiles() {
+void TileManager::SortTiles(TileRefVector* tiles) {
   TRACE_EVENT0("cc", "TileManager::SortTiles");
 
   // Sort by bin, resolution and time until needed.
-  std::sort(tiles_.begin(), tiles_.end(), BinComparator());
+  std::sort(tiles->begin(), tiles->end(), BinComparator());
+}
+
+void TileManager::GetSortedTiles(TileRefVector* tiles) {
+  TRACE_EVENT0("cc", "TileManager::GetSortedTiles");
+
+  DCHECK_EQ(0u, tiles->size());
+
+  tiles->reserve(tiles_.size());
+  for (TileMap::const_iterator it = tiles_.begin(); it != tiles_.end(); ++it)
+    tiles->push_back(make_scoped_refptr(it->second));
+
+  AssignBinsToTiles(tiles);
+  SortTiles(tiles);
 }
 
 void TileManager::ManageTiles() {
   TRACE_EVENT0("cc", "TileManager::ManageTiles");
-  AssignBinsToTiles();
-  SortTiles();
-  AssignGpuMemoryToTiles();
+
+  // Clear |sorted_tiles_| so that tiles kept alive by it can be freed.
+  sorted_tiles_.clear();
+
+  GetSortedTiles(&sorted_tiles_);
+
+  TileVector tiles_that_need_to_be_rasterized;
+  TileSet oom_tiles_required_for_activation;
+  AssignGpuMemoryToTiles(sorted_tiles_,
+                         &tiles_that_need_to_be_rasterized,
+                         &oom_tiles_required_for_activation);
+  all_tiles_required_for_activation_have_memory_ =
+      oom_tiles_required_for_activation.empty();
   CleanUpUnusedImageDecodeTasks();
 
   TRACE_EVENT_INSTANT1(
       "cc", "DidManage", TRACE_EVENT_SCOPE_THREAD,
       "state", TracedValue::FromValue(BasicStateAsValue().release()));
 
   // Finally, schedule rasterizer tasks.
-  ScheduleTasks();
+  ScheduleTasks(tiles_that_need_to_be_rasterized);
 }
 
 void TileManager::CheckForCompletedTileUploads() {
   raster_worker_pool_->CheckForCompletedTasks();
 
   if (did_initialize_visible_tile_) {
     client_->DidInitializeVisibleTile();
     did_initialize_visible_tile_ = false;
   }
 }
 
 void TileManager::GetMemoryStats(
     size_t* memory_required_bytes,
     size_t* memory_nice_to_have_bytes,
     size_t* memory_used_bytes) const {
   *memory_required_bytes = 0;
   *memory_nice_to_have_bytes = 0;
   *memory_used_bytes = resource_pool_->acquired_memory_usage_bytes();
-  for (TileVector::const_iterator it = tiles_.begin();
+  for (TileMap::const_iterator it = tiles_.begin();
        it != tiles_.end();
        ++it) {
-    const Tile* tile = *it;
+    const Tile* tile = it->second;
     const ManagedTileState& mts = tile->managed_state();
 
     RasterMode mode = HIGH_QUALITY_RASTER_MODE;
     if (tile->IsReadyToDraw(&mode) &&
         !mts.tile_versions[mode].requires_resource())
       continue;
 
     size_t tile_bytes = tile->bytes_consumed_if_allocated();
     if (mts.gpu_memmgr_stats_bin == NOW_BIN)
       *memory_required_bytes += tile_bytes;
     if (mts.gpu_memmgr_stats_bin != NEVER_BIN)
       *memory_nice_to_have_bytes += tile_bytes;
   }
 }
 
 scoped_ptr<base::Value> TileManager::BasicStateAsValue() const {
   scoped_ptr<base::DictionaryValue> state(new base::DictionaryValue());
   state->SetInteger("tile_count", tiles_.size());
   state->Set("global_state", global_state_.AsValue().release());
   state->Set("memory_requirements", GetMemoryRequirementsAsValue().release());
   return state.PassAs<base::Value>();
 }
 
 scoped_ptr<base::Value> TileManager::AllTilesAsValue() const {
   scoped_ptr<base::ListValue> state(new base::ListValue());
-  for (TileVector::const_iterator it = tiles_.begin();
+  for (TileMap::const_iterator it = tiles_.begin();
        it != tiles_.end();
        it++) {
-    state->Append((*it)->AsValue().release());
+    state->Append(it->second->AsValue().release());
   }
   return state.PassAs<base::Value>();
 }
 
 scoped_ptr<base::Value> TileManager::GetMemoryRequirementsAsValue() const {
   scoped_ptr<base::DictionaryValue> requirements(
       new base::DictionaryValue());
 
   size_t memory_required_bytes;
   size_t memory_nice_to_have_bytes;
   size_t memory_used_bytes;
   GetMemoryStats(&memory_required_bytes,
                  &memory_nice_to_have_bytes,
                  &memory_used_bytes);
   requirements->SetInteger("memory_required_bytes", memory_required_bytes);
   requirements->SetInteger("memory_nice_to_have_bytes",
                            memory_nice_to_have_bytes);
   requirements->SetInteger("memory_used_bytes", memory_used_bytes);
   return requirements.PassAs<base::Value>();
 }
 
-void TileManager::AddRequiredTileForActivation(Tile* tile) {
-  DCHECK(std::find(tiles_that_need_to_be_initialized_for_activation_.begin(),
-                   tiles_that_need_to_be_initialized_for_activation_.end(),
-                   tile) ==
-         tiles_that_need_to_be_initialized_for_activation_.end());
-  tiles_that_need_to_be_initialized_for_activation_.insert(tile);
-}
-
 RasterMode TileManager::DetermineRasterMode(const Tile* tile) const {
   DCHECK(tile);
   DCHECK(tile->picture_pile());
 
   RasterMode raster_mode;
 
   if (tile->managed_state().resolution == LOW_RESOLUTION)
     raster_mode = LOW_QUALITY_RASTER_MODE;
   else if (!tile->picture_pile()->can_use_lcd_text())
     raster_mode = HIGH_QUALITY_NO_LCD_RASTER_MODE;
   else
     raster_mode = HIGH_QUALITY_RASTER_MODE;
 
   return raster_mode;
 }
 
-void TileManager::AssignGpuMemoryToTiles() {
+void TileManager::AssignGpuMemoryToTiles(
+    const TileRefVector& sorted_tiles,
+    TileVector* tiles_that_need_to_be_rasterized,
+    TileSet* oom_tiles_required_for_activation) {
   TRACE_EVENT0("cc", "TileManager::AssignGpuMemoryToTiles");
 
+  // Reset activation tiles flag, to ensure we can activate
+  // if we don't have any required-for-activation tiles here.
+  all_tiles_required_for_activation_have_been_initialized_ = true;
+
   // Now give memory out to the tiles until we're out, and build
   // the needs-to-be-rasterized queue.
-  tiles_that_need_to_be_rasterized_.clear();
-  tiles_that_need_to_be_initialized_for_activation_.clear();
-  oom_tiles_that_need_to_be_initialized_for_activation_.clear();
-
   size_t bytes_releasable = 0;
-  for (TileVector::const_iterator it = tiles_.begin();
-       it != tiles_.end();
+  for (TileRefVector::const_iterator it = sorted_tiles.begin();
+       it != sorted_tiles.end();
        ++it) {
-    const Tile* tile = *it;
+    const Tile* tile = it->get();
     const ManagedTileState& mts = tile->managed_state();
     for (int mode = 0; mode < NUM_RASTER_MODES; ++mode) {
       if (mts.tile_versions[mode].resource_)
         bytes_releasable += tile->bytes_consumed_if_allocated();
     }
   }
 
   // Cast to prevent overflow.
   int64 bytes_available =
       static_cast<int64>(bytes_releasable) +
       static_cast<int64>(global_state_.memory_limit_in_bytes) -
       static_cast<int64>(resource_pool_->acquired_memory_usage_bytes());
 
   size_t bytes_allocatable =
       std::max(static_cast<int64>(0), bytes_available);
 
   size_t bytes_that_exceeded_memory_budget = 0;
   size_t bytes_left = bytes_allocatable;
   size_t bytes_oom_tiles_that_need_to_be_initialized_for_activation = 0;
   bool higher_priority_tile_oomed = false;
-  for (TileVector::iterator it = tiles_.begin();
-       it != tiles_.end();
+  for (TileRefVector::const_iterator it = sorted_tiles.begin();
+       it != sorted_tiles.end();
        ++it) {
-    Tile* tile = *it;
+    Tile* tile = it->get();
     ManagedTileState& mts = tile->managed_state();
 
     // Pick the better version out of the one we already set,
     // and the one that is required.
     mts.raster_mode = std::min(mts.raster_mode, DetermineRasterMode(tile));
 
     ManagedTileState::TileVersion& tile_version =
         mts.tile_versions[mts.raster_mode];
 
     // If this tile doesn't need a resource, then nothing to do.
@@ skipping 20 matching lines @@
       tile_bytes += tile->bytes_consumed_if_allocated();
 
     // Tile is OOM.
     if (tile_bytes > bytes_left) {
       if (tile->required_for_activation()) {
         // Immediately mark tiles for on-demand raster once the amount
         // of memory for oom tiles required for activation exceeds our
         // memory limit.
         if (bytes_oom_tiles_that_need_to_be_initialized_for_activation <
             global_state_.memory_limit_in_bytes) {
-          oom_tiles_that_need_to_be_initialized_for_activation_.insert(tile);
+          oom_tiles_required_for_activation->insert(tile);
           bytes_oom_tiles_that_need_to_be_initialized_for_activation +=
               tile_bytes;
         } else {
           tile_version.set_rasterize_on_demand();
         }
       }
       FreeResourcesForTile(tile);
       higher_priority_tile_oomed = true;
       bytes_that_exceeded_memory_budget += tile_bytes;
       continue;
     }
 
     tile_version.set_use_resource();
     bytes_left -= tile_bytes;
 
     // Tile shouldn't be rasterized if we've failed to assign
     // gpu memory to a higher priority tile. This is important for
     // two reasons:
     // 1. Tile size should not impact raster priority.
     // 2. Tile with unreleasable memory could otherwise incorrectly
     //    be added as it's not affected by |bytes_allocatable|.
     if (higher_priority_tile_oomed)
       continue;
 
     if (!tile_version.resource_)
-      tiles_that_need_to_be_rasterized_.push_back(tile);
+      tiles_that_need_to_be_rasterized->push_back(tile);
 
     if (!tile->IsReadyToDraw(NULL) &&
         tile->required_for_activation()) {
-      AddRequiredTileForActivation(tile);
+      all_tiles_required_for_activation_have_been_initialized_ = false;
     }
   }
 
   ever_exceeded_memory_budget_ |= bytes_that_exceeded_memory_budget > 0;
   if (ever_exceeded_memory_budget_) {
       TRACE_COUNTER_ID2("cc", "over_memory_budget", this,
                         "budget", global_state_.memory_limit_in_bytes,
                         "over", bytes_that_exceeded_memory_budget);
   }
   memory_stats_from_last_assign_.total_budget_in_bytes =
       global_state_.memory_limit_in_bytes;
   memory_stats_from_last_assign_.bytes_allocated =
       bytes_allocatable - bytes_left;
   memory_stats_from_last_assign_.bytes_unreleasable =
       bytes_allocatable - bytes_releasable;
   memory_stats_from_last_assign_.bytes_over =
       bytes_that_exceeded_memory_budget;
 }
 
-void TileManager::ReassignGpuMemoryToOOMTilesRequiredForActivation() {
+void TileManager::ReassignGpuMemoryToOOMTilesRequiredForActivation(
+    const TileRefVector& sorted_tiles,
+    TileVector* tiles_that_need_to_be_rasterized,
+    TileSet* oom_tiles_required_for_activation) {
   TRACE_EVENT0(
       "cc", "TileManager::ReassignGpuMemoryToOOMTilesRequiredForActivation");
 
   size_t bytes_oom_for_required_tiles = 0;
   TileVector tiles_requiring_memory_but_oomed;
-  for (TileVector::iterator it = tiles_.begin(); it != tiles_.end(); ++it) {
-    Tile* tile = *it;
-    if (oom_tiles_that_need_to_be_initialized_for_activation_.find(tile) ==
-        oom_tiles_that_need_to_be_initialized_for_activation_.end())
+  for (TileRefVector::const_iterator it = sorted_tiles.begin();
+       it != sorted_tiles.end();
+       ++it) {
+    Tile* tile = it->get();
+    if (oom_tiles_required_for_activation->find(tile) ==
+        oom_tiles_required_for_activation->end())
       continue;
 
     tiles_requiring_memory_but_oomed.push_back(tile);
     bytes_oom_for_required_tiles += tile->bytes_consumed_if_allocated();
   }
 
   if (tiles_requiring_memory_but_oomed.empty())
     return;
 
-  // In OOM situation, we iterate tiles_, remove the memory for active tree
-  // and not the now bin. And give them to bytes_oom_for_required_tiles
+  // In OOM situation, we iterate sorted_tiles, remove the memory for active
+  // tree and not the now bin. And give them to bytes_oom_for_required_tiles
   size_t bytes_freed = 0;
-  for (TileVector::reverse_iterator it = tiles_.rbegin();
-       it != tiles_.rend(); ++it) {
-    Tile* tile = *it;
+  for (TileRefVector::const_reverse_iterator it = sorted_tiles.rbegin();
+       it != sorted_tiles.rend();
+       ++it) {
+    Tile* tile = it->get();
     ManagedTileState& mts = tile->managed_state();
     if (mts.tree_bin[PENDING_TREE] == NEVER_BIN &&
         mts.tree_bin[ACTIVE_TREE] != NOW_BIN) {
       ManagedTileState::TileVersion& tile_version =
           mts.tile_versions[mts.raster_mode];
 
       // If the tile is in the to-rasterize list, but it has no task,
       // then it means that we have assigned memory for it.
       TileVector::iterator raster_it =
-          std::find(tiles_that_need_to_be_rasterized_.begin(),
-                    tiles_that_need_to_be_rasterized_.end(),
+          std::find(tiles_that_need_to_be_rasterized->begin(),
+                    tiles_that_need_to_be_rasterized->end(),
                     tile);
-      if (raster_it != tiles_that_need_to_be_rasterized_.end() &&
+      if (raster_it != tiles_that_need_to_be_rasterized->end() &&
           tile_version.raster_task_.is_null()) {
         bytes_freed += tile->bytes_consumed_if_allocated();
-        tiles_that_need_to_be_rasterized_.erase(raster_it);
+        tiles_that_need_to_be_rasterized->erase(raster_it);
       }
 
       // Also consider all of the completed resources for freeing.
       for (int mode = 0; mode < NUM_RASTER_MODES; ++mode) {
         if (mts.tile_versions[mode].resource_) {
           DCHECK(!tile->required_for_activation());
           FreeResourceForTile(tile, static_cast<RasterMode>(mode));
           bytes_freed += tile->bytes_consumed_if_allocated();
         }
       }
     }
 
     if (bytes_oom_for_required_tiles <= bytes_freed)
       break;
   }
 
   for (TileVector::iterator it = tiles_requiring_memory_but_oomed.begin();
        it != tiles_requiring_memory_but_oomed.end() && bytes_freed > 0;
        ++it) {
     Tile* tile = *it;
     ManagedTileState& mts = tile->managed_state();
     size_t bytes_needed = tile->bytes_consumed_if_allocated();
     if (bytes_needed > bytes_freed)
       continue;
     mts.tile_versions[mts.raster_mode].set_use_resource();
     bytes_freed -= bytes_needed;
-    tiles_that_need_to_be_rasterized_.push_back(tile);
+    tiles_that_need_to_be_rasterized->push_back(tile);
     DCHECK(tile->required_for_activation());
-    AddRequiredTileForActivation(tile);
-    oom_tiles_that_need_to_be_initialized_for_activation_.erase(tile);
+    all_tiles_required_for_activation_have_been_initialized_ = false;
+    oom_tiles_required_for_activation->erase(tile);
   }
 }
 
 void TileManager::CleanUpUnusedImageDecodeTasks() {
   // Calculate a set of layers that are used by at least one tile.
   base::hash_set<int> used_layers;
-  for (TileVector::iterator it = tiles_.begin(); it != tiles_.end(); ++it)
-    used_layers.insert((*it)->layer_id());
+  for (TileMap::iterator it = tiles_.begin(); it != tiles_.end(); ++it)
+    used_layers.insert(it->second->layer_id());
 
   // Now calculate the set of layers in |image_decode_tasks_| that are not used
   // by any tile.
   std::vector<int> unused_layers;
   for (LayerPixelRefTaskMap::iterator it = image_decode_tasks_.begin();
        it != image_decode_tasks_.end();
        ++it) {
     if (used_layers.find(it->first) == used_layers.end())
       unused_layers.push_back(it->first);
   }
@@ skipping 22 matching lines @@
 
 void TileManager::FreeUnusedResourcesForTile(Tile* tile) {
   RasterMode used_mode = HIGH_QUALITY_RASTER_MODE;
   bool version_is_used = tile->IsReadyToDraw(&used_mode);
   for (int mode = 0; mode < NUM_RASTER_MODES; ++mode) {
     if (!version_is_used || mode != used_mode)
       FreeResourceForTile(tile, static_cast<RasterMode>(mode));
   }
 }
 
-void TileManager::ScheduleTasks() {
+void TileManager::ScheduleTasks(
+    const TileVector& tiles_that_need_to_be_rasterized) {
   TRACE_EVENT1("cc", "TileManager::ScheduleTasks",
-               "count", tiles_that_need_to_be_rasterized_.size());
+               "count", tiles_that_need_to_be_rasterized.size());
   RasterWorkerPool::RasterTask::Queue tasks;
 
   // Build a new task queue containing all task currently needed. Tasks
   // are added in order of priority, highest priority task first.
-  for (TileVector::iterator it = tiles_that_need_to_be_rasterized_.begin();
-       it != tiles_that_need_to_be_rasterized_.end();
+  for (TileVector::const_iterator it = tiles_that_need_to_be_rasterized.begin();
+       it != tiles_that_need_to_be_rasterized.end();
        ++it) {
     Tile* tile = *it;
     ManagedTileState& mts = tile->managed_state();
     ManagedTileState::TileVersion& tile_version =
         mts.tile_versions[mts.raster_mode];
 
     DCHECK(tile_version.requires_resource());
     DCHECK(!tile_version.resource_);
 
     if (tile_version.raster_task_.is_null())
@@ skipping 60 matching lines @@
       mts.raster_mode,
       use_color_estimator_,
       mts.tree_bin[PENDING_TREE] == NOW_BIN,
       mts.resolution,
       tile->layer_id(),
       &tile,
       tile->source_frame_number(),
       rendering_stats_instrumentation_,
       base::Bind(&TileManager::OnRasterTaskCompleted,
                  base::Unretained(this),
-                 make_scoped_refptr(tile),
+                 tile->id(),
                  base::Passed(&resource),
                  mts.raster_mode),
       &decode_tasks);
 }
 
 void TileManager::OnImageDecodeTaskCompleted(
     int layer_id,
     skia::LazyPixelRef* pixel_ref,
     bool was_canceled) {
   // If the task was canceled, we need to clean it up
   // from |image_decode_tasks_|.
   if (!was_canceled)
     return;
 
   LayerPixelRefTaskMap::iterator layer_it =
       image_decode_tasks_.find(layer_id);
 
   if (layer_it == image_decode_tasks_.end())
     return;
 
   PixelRefTaskMap& pixel_ref_tasks = layer_it->second;
   PixelRefTaskMap::iterator task_it =
       pixel_ref_tasks.find(pixel_ref->getGenerationID());
 
   if (task_it != pixel_ref_tasks.end())
     pixel_ref_tasks.erase(task_it);
 }
 
 void TileManager::OnRasterTaskCompleted(
-    scoped_refptr<Tile> tile,
+    Tile::Id tile_id,
     scoped_ptr<ResourcePool::Resource> resource,
     RasterMode raster_mode,
     const PicturePileImpl::Analysis& analysis,
     bool was_canceled) {
   TRACE_EVENT1("cc", "TileManager::OnRasterTaskCompleted",
                "was_canceled", was_canceled);
 
+  TileMap::iterator it = tiles_.find(tile_id);
+  if (it == tiles_.end()) {
+    resource_pool_->ReleaseResource(resource.Pass());
+    return;
+  }
+
+  Tile* tile = it->second;
   ManagedTileState& mts = tile->managed_state();
   ManagedTileState::TileVersion& tile_version =
       mts.tile_versions[raster_mode];
   DCHECK(!tile_version.raster_task_.is_null());
   tile_version.raster_task_.Reset();
 
   if (was_canceled) {
     resource_pool_->ReleaseResource(resource.Pass());
     return;
   }
 
   tile_version.set_has_text(analysis.has_text);
   if (analysis.is_solid_color) {
     tile_version.set_solid_color(analysis.solid_color);
     resource_pool_->ReleaseResource(resource.Pass());
   } else {
     tile_version.resource_ = resource.Pass();
   }
 
-  FreeUnusedResourcesForTile(tile.get());
+  FreeUnusedResourcesForTile(tile);
 
-  DidFinishTileInitialization(tile.get());
-}
-
-void TileManager::DidFinishTileInitialization(Tile* tile) {
   if (tile->priority(ACTIVE_TREE).distance_to_visible_in_pixels == 0)
     did_initialize_visible_tile_ = true;
-  if (tile->required_for_activation()) {
-    // It's possible that a tile required for activation is not in this list
-    // if it was marked as being required after being dispatched for
-    // rasterization but before AssignGPUMemory was called again.
-    tiles_that_need_to_be_initialized_for_activation_.erase(tile);
-  }
-}
-
-void TileManager::DidTileTreeBinChange(Tile* tile,
-                                       ManagedTileBin new_tree_bin,
-                                       WhichTree tree) {
-  ManagedTileState& mts = tile->managed_state();
-  mts.tree_bin[tree] = new_tree_bin;
 }
 
 }  // namespace cc