cc: Add tiling raster tile iterators.

cc/resources/tile.cc

Index: cc/resources/tile.cc
diff --git a/cc/resources/tile.cc b/cc/resources/tile.cc
index 7b1f00aee760db3b0446bc2f3b45690059078ccd..65a17387dd3edeaf5e741053a11bbe9396bd14ff 100644
--- a/cc/resources/tile.cc
+++ b/cc/resources/tile.cc
@@ -4,6 +4,8 @@
 
 #include "cc/resources/tile.h"
 
+#include <algorithm>
+
 #include "cc/base/math_util.h"
 #include "cc/debug/traced_value.h"
 #include "cc/resources/tile_manager.h"
@@ -81,4 +83,27 @@ size_t Tile::GPUMemoryUsageInBytes() const {
   return total_size;
 }
 
+RasterMode Tile::DetermineRasterModeForTree(WhichTree tree) const {
+  return DetermineRasterModeForResolution(priority(tree).resolution);
+}
+
+RasterMode Tile::DetermineOverallRasterMode() const {
+  return DetermineRasterModeForResolution(managed_state_.resolution);
+}
+
+RasterMode Tile::DetermineRasterModeForResolution(
+    TileResolution resolution) const {
+  RasterMode current_mode = managed_state_.raster_mode;
+  RasterMode raster_mode = HIGH_QUALITY_RASTER_MODE;
+  if (resolution == LOW_RESOLUTION)
+    raster_mode = LOW_QUALITY_RASTER_MODE;
+  else if (can_use_lcd_text())
+    raster_mode = HIGH_QUALITY_RASTER_MODE;
+  else if (managed_state_.tile_versions[current_mode].has_text_ ||
+           !managed_state_.tile_versions[current_mode].IsReadyToDraw())
+    raster_mode = HIGH_QUALITY_NO_LCD_RASTER_MODE;
+
+  return std::min(raster_mode, current_mode);
+}
+
 }  // namespace cc