2 files changed, 14 insertions, 4 deletions
diff --git a/cc/layers/picture_layer_impl.cc b/cc/layers/picture_layer_impl.cc
index 93d9bf1..695f539 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -52,6 +52,10 @@ const int kMinHeightForGpuRasteredTile = 256;
 // of using the same tile size.
 const int kTileRoundUp = 64;
 
+// For performance reasons and to support compressed tile textures, tile
+// width and height should be an even multiple of 4 in size.
+const int kTileMinimalAlignment = 4;
+
 }  // namespace
 
 namespace cc {
@@ -781,6 +785,10 @@ gfx::Size PictureLayerImpl::CalculateTileSize(
     tile_height = std::min(tile_height, default_tile_height);
   }
 
+  // Ensure that tile width and height are properly aligned.
+  tile_width = MathUtil::UncheckedRoundUp(tile_width, kTileMinimalAlignment);
+  tile_height = MathUtil::UncheckedRoundUp(tile_height, kTileMinimalAlignment);
+
   // Under no circumstance should we be larger than the max texture size.
   tile_width = std::min(tile_width, max_texture_size);
   tile_height = std::min(tile_height, max_texture_size);
diff --git a/cc/layers/picture_layer_impl_unittest.cc b/cc/layers/picture_layer_impl_unittest.cc
index 0f73ef1..04bac67 100644
--- a/cc/layers/picture_layer_impl_unittest.cc
+++ b/cc/layers/picture_layer_impl_unittest.cc
@@ -4890,8 +4890,10 @@ TEST_F(TileSizeTest, TileSizes) {
 
   layer->set_gpu_raster_max_texture_size(host_impl_.device_viewport_size());
   result = layer->CalculateTileSize(gfx::Size(10000, 10000));
-  EXPECT_EQ(result.width(), 2000 + 2 * PictureLayerTiling::kBorderTexels);
-  EXPECT_EQ(result.height(), 500 + 2);
+  EXPECT_EQ(result.width(),
+            MathUtil::UncheckedRoundUp(
+                2000 + 2 * PictureLayerTiling::kBorderTexels, 4));
+  EXPECT_EQ(result.height(), 504);  // 500 + 2, 4-byte aligned.
 
   // Clamp and round-up, when smaller than viewport.
   // Tile-height doubles to 50% when width shrinks to <= 50%.
@@ -4899,7 +4901,7 @@ TEST_F(TileSizeTest, TileSizes) {
   layer->set_gpu_raster_max_texture_size(host_impl_.device_viewport_size());
   result = layer->CalculateTileSize(gfx::Size(447, 10000));
   EXPECT_EQ(result.width(), 448);
-  EXPECT_EQ(result.height(), 500 + 2);
+  EXPECT_EQ(result.height(), 504);  // 500 + 2, 4-byte aliged.
 
   // Largest layer is 50% of viewport width (rounded up), and
   // 50% of viewport in height.
@@ -4908,7 +4910,7 @@ TEST_F(TileSizeTest, TileSizes) {
   EXPECT_EQ(result.height(), 448);
   result = layer->CalculateTileSize(gfx::Size(500, 499));
   EXPECT_EQ(result.width(), 512);
-  EXPECT_EQ(result.height(), 500 + 2);
+  EXPECT_EQ(result.height(), 504);  // 500 + 2, 4-byte aligned.
 }
 
 TEST_F(NoLowResPictureLayerImplTest, LowResWasHighResCollision) {