cc: Fix memory limit edge cases for SetIsLikelyToRequireADraw.

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 71f2e83017547d2aa9131b37c619bf8bee749041..b86b1a0d66396ba3bbe85aa5daec8761d971723e 100644
--- a/cc/resources/tile_manager.cc
+++ b/cc/resources/tile_manager.cc
@@ -426,6 +426,11 @@ void TileManager::SynchronouslyRasterizeTiles(
                          std::numeric_limits<size_t>::max(),
                          &tiles_that_need_to_be_rasterized);
 
+  // Since we are synchronously rasterizing all tiles, we don't require further
+  // draws for that. Set the flag to false so that we can clear it if it was set
+  // earlier by PrepareTiles.
+  client_->SetIsLikelyToRequireADraw(false);

[vmpstr, 2015/03/27 17:23:28]

Just FYI, this function is kind of slated for removal. crbug.com/457860

[sunnyps, 2015/03/27 18:38:04]

Yeah, would be nice to keep the test while it's alive.

+
   // We must reduce the amount of unused resources before calling
   // RunTasks to prevent usage from rising above limits.
   resource_pool_->ReduceResourceUsage();
@@ -876,6 +881,10 @@ void TileManager::SetTileTaskRunnerForTesting(
   tile_task_runner_->SetClient(this);
 }
 
+void TileManager::CheckIfMoreTilesNeedToBePreparedForTesting() {
+  CheckIfMoreTilesNeedToBePrepared();

[vmpstr, 2015/03/27 17:23:28]

Feel free to inline this. (We don't typically implement ForTesting functionality
in .cc)

[sunnyps, 2015/03/27 18:38:04]

Done.

+}
+
 bool TileManager::AreRequiredTilesReadyToDraw(
     RasterTilePriorityQueue::Type type) const {
   scoped_ptr<RasterTilePriorityQueue> raster_priority_queue(
@@ -961,6 +970,12 @@ void TileManager::CheckIfMoreTilesNeedToBePrepared() {
                          scheduled_raster_task_limit_,
                          &tiles_that_need_to_be_rasterized);
 
+  // Inform the client that will likely require a draw if the highest priority
+  // tile that will be rasterized is required for draw.
+  client_->SetIsLikelyToRequireADraw(
+      !tiles_that_need_to_be_rasterized.empty() &&
+      (*tiles_that_need_to_be_rasterized.begin())->required_for_draw());
+
   // |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()) {