cc: Prevent the tile manager from allocating more memory than allowed.

cc/resources/tile_manager.cc

Index: cc/resources/tile_manager.cc
diff --git a/cc/resources/tile_manager.cc b/cc/resources/tile_manager.cc
index 86de61041b2c7f0da7abb96474970e064a2b465f..cff5883078b9c86ed91783f0b66222ec8b381c7f 100644
--- a/cc/resources/tile_manager.cc
+++ b/cc/resources/tile_manager.cc
@@ -180,7 +180,7 @@ TileManager::~TileManager() {
 void TileManager::SetGlobalState(
     const GlobalStateThatImpactsTilePriority& global_state) {
   global_state_ = global_state;
-  resource_pool_->SetMemoryUsageLimits(
+  resource_pool_->SetResourceUsageLimits(
       global_state_.memory_limit_in_bytes,
       global_state_.unused_memory_limit_in_bytes,
       global_state_.num_resources_limit);
@@ -499,9 +499,10 @@ void TileManager::AssignGpuMemoryToTiles(
       static_cast<int64>(bytes_releasable_) +
       static_cast<int64>(global_state_.memory_limit_in_bytes) -
       static_cast<int64>(resource_pool_->acquired_memory_usage_bytes());
-  int resources_available = resources_releasable_ +
-                            global_state_.num_resources_limit -
-                            resource_pool_->NumResources();
+  int resources_available =
+      resources_releasable_ +
+      global_state_.num_resources_limit -
+      resource_pool_->acquired_resource_count();
 
   size_t bytes_allocatable =
       std::max(static_cast<int64>(0), bytes_available);
@@ -705,6 +706,10 @@ void TileManager::ScheduleTasks(
     tasks.Append(tile_version.raster_task_, tile->required_for_activation());
   }
 
+  // We must reduce the amount of unused resoruces before calling
+  // ScheduleTasks to prevent usage from rising above limits.
+  resource_pool_->ReduceResourceUsage();
+
   // Schedule running of |tasks|. This replaces any previously
   // scheduled tasks and effectively cancels all tasks not present
   // in |tasks|.