[4/5] Add translated rasterization support for PictureLayerTilingSet & below

cc/tiles/picture_layer_tiling.h

Index: cc/tiles/picture_layer_tiling.h
diff --git a/cc/tiles/picture_layer_tiling.h b/cc/tiles/picture_layer_tiling.h
index b718ca1882a0839b66c99f870912c8c6be51aa7f..116baf5eec9476714d28013b38a5b4f2b6dcbd76 100644
--- a/cc/tiles/picture_layer_tiling.h
+++ b/cc/tiles/picture_layer_tiling.h
@@ -16,6 +16,7 @@
 
 #include "base/macros.h"
 #include "cc/base/region.h"
+#include "cc/base/scale_translate2d.h"
 #include "cc/base/tiling_data.h"
 #include "cc/cc_export.h"
 #include "cc/tiles/tile.h"
@@ -81,7 +82,7 @@ class CC_EXPORT PictureLayerTiling {
   static const int kBorderTexels = 1;
 
   PictureLayerTiling(WhichTree tree,
-                     float raster_scale,
+                     const ScaleTranslate2d& raster_transform,
                      scoped_refptr<RasterSource> raster_source,
                      PictureLayerTilingClient* client,
                      float min_preraster_distance,
@@ -120,7 +121,8 @@ class CC_EXPORT PictureLayerTiling {
   gfx::Size tiling_size() const { return tiling_data_.tiling_size(); }
   gfx::Rect live_tiles_rect() const { return live_tiles_rect_; }
   gfx::Size tile_size() const { return tiling_data_.max_texture_size(); }
-  float contents_scale() const { return contents_scale_; }
+  float contents_scale_key() const { return raster_transform_.scale(); }

[enne (OOO), 2017/03/29 12:57:37]

Can you leave some more documentation here about how key relates to everything
else? I think this might be confusing to people who aren't familiar with these
classes.  Maybe at least saying that tilings have a unique scale, and then also
have a fixed translation to adjust for pixel alignment.  And also maybe that we
don't ever have tilings with the same scale and different translations, so the
scale itself can be used as the key to identify the tiling?

[trchen, 2017/03/30 22:17:32]

Done.

+  const ScaleTranslate2d& raster_transform() const { return raster_transform_; }
   const TilingData* tiling_data() const { return &tiling_data_; }
 
   Tile* TileAt(int i, int j) const {
@@ -169,7 +171,7 @@ class CC_EXPORT PictureLayerTiling {
 
   void SetAllTilesOccludedForTesting() {
     gfx::Rect viewport_in_layer_space =
-        ScaleToEnclosingRect(current_visible_rect_, 1.f / contents_scale_);
+        EnclosingLayerRectFromContentsRect(current_visible_rect_);
     current_occlusion_in_layer_space_ =
         Occlusion(gfx::Transform(),
                   SimpleEnclosedRegion(viewport_in_layer_space),
@@ -220,7 +222,7 @@ class CC_EXPORT PictureLayerTiling {
     const PictureLayerTiling* tiling_ = nullptr;
     gfx::Size coverage_rect_max_bounds_;
     gfx::Rect coverage_rect_;
-    float coverage_to_content_scale_;
+    ScaleTranslate2d coverage_to_content_;
 
     Tile* current_tile_ = nullptr;
     gfx::Rect current_geometry_rect_;
@@ -330,8 +332,13 @@ class CC_EXPORT PictureLayerTiling {
   }
   void RemoveTilesInRegion(const Region& layer_region, bool recreate_tiles);
 
+  gfx::Rect EnclosingContentsRectFromLayerRect(
+      const gfx::Rect& layer_rect) const;
+  gfx::Rect EnclosingLayerRectFromContentsRect(
+      const gfx::Rect& contents_rect) const;
+
   // Given properties.
-  const float contents_scale_;
+  const ScaleTranslate2d raster_transform_;
   PictureLayerTilingClient* const client_;
   const WhichTree tree_;
   scoped_refptr<RasterSource> raster_source_;
@@ -353,7 +360,7 @@ class CC_EXPORT PictureLayerTiling {
   gfx::Rect current_soon_border_rect_;
   gfx::Rect current_eventually_rect_;
   // Other properties used for tile iteration and prioritization.
-  float current_content_to_screen_scale_;
+  float current_content_to_screen_scale_ = 0.f;
   Occlusion current_occlusion_in_layer_space_;
   float max_skewport_extent_in_screen_space_ = 0.f;