cc: Default value for use_distance_field_text was not set in the layer tree settings

This was causing many ResourceProviders to be created with distance field text randomly set to on or off.  Because AcquireSkSurface was never called on those instances of ResourceProvider, it isn't a serious problem, but I fixed it anyway, safer this way.

Review URL: https://codereview.chromium.org/601243003

Cr-Commit-Position: refs/heads/master@{#296742}

cc/trees/layer_tree_settings.cc

@@ -26,6 +26,7 @@ LayerTreeSettings::LayerTreeSettings()
       partial_swap_enabled(false),
       accelerated_animation_enabled(true),
       can_use_lcd_text(true),
+      use_distance_field_text(false),
       should_clear_root_render_pass(true),
       gpu_rasterization_enabled(false),
       gpu_rasterization_forced(false),