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 68 matching lines @@
 TileManager::TileManager(
     TileManagerClient* client,
     ResourceProvider* resource_provider,
     scoped_ptr<RasterWorkerPool> raster_worker_pool,
     size_t num_raster_threads,
     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),
       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();
+
+  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::UpdateSortedTiles() {
+  TRACE_EVENT0("cc", "TileManager::UpdateSortedTiles");
+
+  // We need to first clear the current sorted tiles, since tiles that are
+  // only kept alive by |sorted_tiles_| need to be freed.
+  sorted_tiles_.clear();
+
+  TileRefVector tiles;
+  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);
+  sorted_tiles_.swap(tiles);
+}
+
 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 26 matching lines @@
     DidTileTreeBinChange(tile,
                          bin_map[BinFromTilePriority(
                              tile->priority(PENDING_TREE), tree_priority)],
                          PENDING_TREE);
 
     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::ManageTiles() {
   TRACE_EVENT0("cc", "TileManager::ManageTiles");
-  AssignBinsToTiles();
-  SortTiles();
-  AssignGpuMemoryToTiles();
+
+  UpdateSortedTiles();

[reveman, 2013/07/09 01:15:37]

I would prefer if you just moved the updatesortedtiles code here. That should
never be done from anywhere else and having the code part of ManageTiles makes
it more clear and deter people from using it elsewhere.

[tomhudson, 2013/07/09 09:06:07]

I like most of your other suggestions to get rid of helper functions, but
UpdateSortedTiles() is a large chunk of work, with a meaningful name, which we
want to independently TRACE... Leaving it broken out into a function (with
perhaps a slightly clearer name?) seems like a win to me.

[reveman, 2013/07/09 15:54:03]

We already have tracing for SortTiles and AssignBinsToTiles so the only part
we're missing is the process of creating the vector from the map. Maybe we
should just move that part to a different function instead of nesting it?

I think we should eventually move the tile map out of the tile manager and
instead have it passed as a parameter to ManageTiles(). That would prevent the
tile manager from incorrectly using unmanaged tiles. Having this code well
aligned with that idea might help prevent incorrect behavior to some degree
without actually moving the tile map.

[vmpstr, 2013/07/09 16:48:18]

I tend to agree with Tom for two reasons: 1. It's a nice separate function that
does a limited amount of work and it's easy to reason about it. 2. It allows us
to test AssignGpuMemory (first UpdateSortedTiles, then AssignGpuMemory). If we
move the code directly in here, then we wouldn't be able to AssignGpuMemory
without doing the sorting ourselves). My plan was to actually write up a few
unittests for just UpdateSortedTiles as well... In the future, we can pass an
unordered set of tiles to UpdateSortedTiles, so that it would construct the
vector from the argument instead of from the class member. Wdyt?

[reveman, 2013/07/09 18:52:29]

Not sure. This function is doing more than the name entails. ie. it's dropping
references which cause tile resources to be freed.

+
+  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();
 
     const ManagedTileState::TileVersion& tile_version =
         tile->GetTileVersionForDrawing();
     if (tile_version.IsReadyToDraw() &&
         !tile_version.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) {

[reveman, 2013/07/09 01:15:37]

I don't think this helper function adds much. The code is probably easier to
read without it.

[vmpstr, 2013/07/09 16:48:18]

Done.

-  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);
+  all_tiles_required_for_activation_have_been_initialized_ = false;
 }
 
 RasterMode TileManager::DetermineRasterMode(const Tile* tile) const {
   DCHECK(tile);
   DCHECK(tile->picture_pile());
 
   const ManagedTileState& mts = tile->managed_state();
   RasterMode current_mode = mts.raster_mode;
 
   RasterMode raster_mode = HIGH_QUALITY_RASTER_MODE;
   if (tile->managed_state().resolution == LOW_RESOLUTION)
     raster_mode = LOW_QUALITY_RASTER_MODE;
   else if (tile->can_use_lcd_text())
     raster_mode = HIGH_QUALITY_RASTER_MODE;
   else if (mts.tile_versions[current_mode].has_text_ ||
            !mts.tile_versions[current_mode].IsReadyToDraw())
     raster_mode = HIGH_QUALITY_NO_LCD_RASTER_MODE;
 
   return std::min(raster_mode, current_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();
 
     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.
     if (!tile_version.requires_resource())
       continue;
@@ skipping 18 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() &&
         tile->required_for_activation()) {
       AddRequiredTileForActivation(tile);
     }
   }
 
   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);
+    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 30 matching lines @@
       break;
     }
   }
 
   for (int mode = 0; mode < NUM_RASTER_MODES; ++mode) {
     if (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 59 matching lines @@
       tile->contents_scale(),
       mts.raster_mode,
       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());
-  DidFinishTileInitialization(tile.get());
+  FreeUnusedResourcesForTile(tile);
+  DidFinishTileInitialization(tile);
 }
 
 void TileManager::DidFinishTileInitialization(Tile* tile) {

[reveman, 2013/07/09 01:15:37]

I don't think this helper function is worth much anymore. Consider moving these
two lines to OnRasterTaskCompleted.

[vmpstr, 2013/07/09 16:48:18]

Done.

   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) {

[reveman, 2013/07/09 01:15:37]

looks like this helper is also just making the code harder to read at this
point. we can fix that in a follow up but I don't mind if you removed it as part
of this patch.

[vmpstr, 2013/07/09 16:48:18]

Done.

   ManagedTileState& mts = tile->managed_state();
   mts.tree_bin[tree] = new_tree_bin;
 }
 
 }  // namespace cc