Allow a layer to use LCD text again

Previously once a layer became not LCD-text capable, it would never
use LCD-text again. I think this was to avoid re-raterization during
animation. As we don't allow LCD text with will-change:transform and
during animation, and we skip re-rasterization on LCD text status
change during animation, there is no reason to keep that logic.

Bug: 1111195
Change-Id: Ib544be76c114e520572c0ccf5d88dd96bf7db151
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2344810Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798939}

cc/layers/picture_layer_impl.cc

@@ -819,10 +819,6 @@ bool PictureLayerImpl::UpdateCanUseLCDText(
   if (!layer_tree_impl()->IsSyncTree())
     return false;
 
-  // Once we disable lcd text, we don't re-enable it.
-  if (!can_use_lcd_text())
-    return false;
-
   auto new_lcd_text_disallowed_reason =
       ComputeLCDTextDisallowedReason(raster_translation_aligns_pixels);
   if (lcd_text_disallowed_reason_ == new_lcd_text_disallowed_reason)

cc/layers/picture_layer_impl_unittest.cc

@@ -5028,11 +5028,10 @@ TEST_F(LegacySWPictureLayerImplTest, UpdateLCDTextInvalidatesPendingTree) {
 
   pending_layer()->SetContentsOpaque(true);
   pending_layer()->UpdateTiles();
-  // Once we disable lcd text, we don't re-enable it.
-  EXPECT_FALSE(pending_layer()->can_use_lcd_text());
+  EXPECT_TRUE(pending_layer()->can_use_lcd_text());
   EXPECT_TRUE(pending_layer()->HighResTiling()->has_tiles());
   for (Tile* tile : pending_layer()->HighResTiling()->AllTilesForTesting())
-    EXPECT_FALSE(tile->can_use_lcd_text());
+    EXPECT_TRUE(tile->can_use_lcd_text());
 }
 
 TEST_F(LegacySWPictureLayerImplTest, UpdateLCDTextPushToActiveTree) {