cc: fix content_to_screen_scale in UpdateTilePriorities.

R=vmpstr@chromium.org, enne@chromium.org, danakj@chromium.org
BUG=403829

Review URL: https://codereview.chromium.org/478723002

Cr-Commit-Position: refs/heads/master@{#290074}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@290074 0039d316-1c4b-4281-b951-d872f2087c98

cc/resources/picture_layer_tiling.cc

@@ -497,8 +497,7 @@ void PictureLayerTiling::UpdateTilePriorities(
   eviction_tiles_cache_valid_ = false;
 
   TilePriority now_priority(resolution_, TilePriority::NOW, 0);
-  float content_to_screen_scale =
-      1.0f / (contents_scale_ * ideal_contents_scale);
+  float content_to_screen_scale = ideal_contents_scale / contents_scale_;
 
   // Assign now priority to all visible tiles.
   bool include_borders = true;

cc/resources/picture_layer_tiling_unittest.cc

@@ -622,13 +622,39 @@ TEST(PictureLayerTilingTest, ViewportDistanceWithScale) {
       ACTIVE_TREE, viewport, 2.0f, 3.0, NULL, NULL, gfx::Transform());
 
   priority = tiling->TileAt(5, 1)->priority(ACTIVE_TREE);
-  EXPECT_FLOAT_EQ(34.f, priority.distance_to_visible);
+  EXPECT_FLOAT_EQ(136.f, priority.distance_to_visible);
 
   priority = tiling->TileAt(2, 5)->priority(ACTIVE_TREE);
-  EXPECT_FLOAT_EQ(14.f, priority.distance_to_visible);
+  EXPECT_FLOAT_EQ(56.f, priority.distance_to_visible);
 
   priority = tiling->TileAt(3, 4)->priority(ACTIVE_TREE);
   EXPECT_FLOAT_EQ(0.f, priority.distance_to_visible);
+
+  // Test additional scales.
+  tiling = TestablePictureLayerTiling::Create(0.2f, layer_bounds, &client);
+  tiling->UpdateTilePriorities(
+      ACTIVE_TREE, viewport, 1.0f, 4.0, NULL, NULL, gfx::Transform());
+
+  priority = tiling->TileAt(5, 1)->priority(ACTIVE_TREE);
+  EXPECT_FLOAT_EQ(110.f, priority.distance_to_visible);
+
+  priority = tiling->TileAt(2, 5)->priority(ACTIVE_TREE);
+  EXPECT_FLOAT_EQ(70.f, priority.distance_to_visible);
+
+  priority = tiling->TileAt(3, 4)->priority(ACTIVE_TREE);
+  EXPECT_FLOAT_EQ(60.f, priority.distance_to_visible);
+
+  tiling->UpdateTilePriorities(
+      ACTIVE_TREE, viewport, 0.5f, 5.0, NULL, NULL, gfx::Transform());
+
+  priority = tiling->TileAt(5, 1)->priority(ACTIVE_TREE);
+  EXPECT_FLOAT_EQ(55.f, priority.distance_to_visible);
+
+  priority = tiling->TileAt(2, 5)->priority(ACTIVE_TREE);
+  EXPECT_FLOAT_EQ(35.f, priority.distance_to_visible);
+
+  priority = tiling->TileAt(3, 4)->priority(ACTIVE_TREE);
+  EXPECT_FLOAT_EQ(30.f, priority.distance_to_visible);
 }
 
 TEST(PictureLayerTilingTest, ExpandRectEqual) {