Raster PictureLayerTiling with fractional translation

cc/raster/raster_buffer_provider.cc

Index: cc/raster/raster_buffer_provider.cc
diff --git a/cc/raster/raster_buffer_provider.cc b/cc/raster/raster_buffer_provider.cc
index 100de97b5fea57fa4253b29114d2de94949b4e51..d0d6ae415bcb5795df99a93b4624d0bc3c9ec0e1 100644
--- a/cc/raster/raster_buffer_provider.cc
+++ b/cc/raster/raster_buffer_provider.cc
@@ -52,6 +52,7 @@ void RasterBufferProvider::PlaybackToMemory(
     const gfx::Rect& canvas_bitmap_rect,
     const gfx::Rect& canvas_playback_rect,
     float scale,
+    const gfx::Vector2dF& translation,
     const RasterSource::PlaybackSettings& playback_settings) {
   TRACE_EVENT0("disabled-by-default-cc.debug",
                "RasterBufferProvider::PlaybackToMemory");
@@ -78,19 +79,25 @@ void RasterBufferProvider::PlaybackToMemory(
     case BGRA_8888: {
       sk_sp<SkSurface> surface =
           SkSurface::MakeRasterDirect(info, memory, stride, &surface_props);
-      raster_source->PlaybackToCanvas(surface->getCanvas(), canvas_bitmap_rect,
-                                      canvas_playback_rect, scale,
-                                      playback_settings);
+      SkCanvas* canvas = surface->getCanvas();
+      canvas->translate(-canvas_bitmap_rect.x(), -canvas_bitmap_rect.y());
+      canvas->clipRect(gfx::RectToSkRect(canvas_playback_rect));
+      canvas->translate(translation.x(), translation.y());
+      canvas->scale(scale, scale);
+      raster_source->PlaybackToCanvas(surface->getCanvas(), playback_settings);
       return;
     }
     case RGBA_4444:
     case ETC1: {
       sk_sp<SkSurface> surface = SkSurface::MakeRaster(info, &surface_props);
+      SkCanvas* canvas = surface->getCanvas();
+      canvas->translate(-canvas_bitmap_rect.x(), -canvas_bitmap_rect.y());
       // TODO(reveman): Improve partial raster support by reducing the size of
-      // playback rect passed to PlaybackToCanvas. crbug.com/519070
-      raster_source->PlaybackToCanvas(surface->getCanvas(), canvas_bitmap_rect,
-                                      canvas_bitmap_rect, scale,
-                                      playback_settings);
+      // the clip rect here. crbug.com/519070
+      canvas->clipRect(gfx::RectToSkRect(canvas_bitmap_rect));
+      canvas->translate(translation.x(), translation.y());
+      canvas->scale(scale, scale);
+      raster_source->PlaybackToCanvas(surface->getCanvas(), playback_settings);
 
       if (format == ETC1) {
         TRACE_EVENT0("cc",