cc: Use multiple PrepareTiles approaches

cc/layers/picture_layer_impl.cc

Index: cc/layers/picture_layer_impl.cc
diff --git a/cc/layers/picture_layer_impl.cc b/cc/layers/picture_layer_impl.cc
index 806ae0a7f67a7dd26cca02a56162458b7ff126b1..fec12b0e6a2fb41ccfcca69042d2da8672a00a16 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -259,8 +259,19 @@ void PictureLayerImpl::AppendQuads(RenderPass* render_pass,
   gfx::Rect scaled_viewport_for_tile_priority = gfx::ScaleToEnclosingRect(
       viewport_rect_for_tile_priority_in_content_space_, max_contents_scale);
 
+  // Determine if num_incomplete_tiles and num_missing_tiles can become 0
+  // if we wait long enough.
+  auto ideal_tiling = tilings_->FindTilingWithScale(ideal_contents_scale_);
+  bool ideal_tiling_visible_tiles_can_be_rasterized =
+      ideal_tiling && ideal_tiling->RasterSourceCoversCurrentVisibleTiles();
+  auto raster_tiling = tilings_->FindTilingWithScale(raster_contents_scale_);
+  bool raster_tiling_visible_tiles_can_be_rasterized =
+      raster_tiling && raster_tiling->RasterSourceCoversCurrentVisibleTiles();
+  append_quads_data->raster_source_covers_visible_high_res_tiles =
+      ideal_tiling_visible_tiles_can_be_rasterized ||
+      raster_tiling_visible_tiles_can_be_rasterized;
+
   size_t missing_tile_count = 0u;
-  size_t on_demand_missing_tile_count = 0u;
   only_used_low_res_last_append_quads_ = true;
   for (PictureLayerTilingSet::CoverageIterator iter(
            tilings_.get(), max_contents_scale,
@@ -366,13 +377,9 @@ void PictureLayerImpl::AppendQuads(RenderPass* render_pass,
   }
 
   if (missing_tile_count) {
-    TRACE_EVENT_INSTANT2("cc",
-                         "PictureLayerImpl::AppendQuads checkerboard",
-                         TRACE_EVENT_SCOPE_THREAD,
-                         "missing_tile_count",
-                         missing_tile_count,
-                         "on_demand_missing_tile_count",
-                         on_demand_missing_tile_count);
+    TRACE_EVENT_INSTANT1("cc", "PictureLayerImpl::AppendQuads checkerboard",
+                         TRACE_EVENT_SCOPE_THREAD, "missing_tile_count",
+                         missing_tile_count);
   }
 
   // Aggressively remove any tilings that are not seen to save memory. Note