cc: Remove unused use_pinch_zoom_scrollbars flag.

The use_pinch_zoom_scrollbars flag is dead.

Review URL: https://codereview.chromium.org/1136843009

Cr-Commit-Position: refs/heads/master@{#329945}

cc/trees/layer_tree_settings.cc

@@ -51,7 +51,6 @@ LayerTreeSettings::LayerTreeSettings()
       max_untiled_layer_size(gfx::Size(512, 512)),
       default_tile_grid_size(gfx::Size(256, 256)),
       minimum_occlusion_tracking_size(gfx::Size(160, 160)),
-      use_pinch_zoom_scrollbars(false),
       use_pinch_virtual_viewport(false),
       tiling_interest_area_viewport_multiplier(9.0f),
       skewport_target_time_in_seconds(1.0f),

cc/trees/layer_tree_settings.h

@@ -64,7 +64,6 @@ class CC_EXPORT LayerTreeSettings {
   gfx::Size max_untiled_layer_size;
   gfx::Size default_tile_grid_size;
   gfx::Size minimum_occlusion_tracking_size;
-  bool use_pinch_zoom_scrollbars;
   bool use_pinch_virtual_viewport;
   float tiling_interest_area_viewport_multiplier;
   float skewport_target_time_in_seconds;

content/renderer/gpu/render_widget_compositor.cc

@@ -425,10 +425,7 @@ void RenderWidgetCompositor::Initialize() {
   if (ui::IsOverlayScrollbarEnabled()) {
     settings.scrollbar_animator = cc::LayerTreeSettings::THINNING;
     settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
-  } else if (cmd->HasSwitch(cc::switches::kEnablePinchVirtualViewport)) {
-    // use_pinch_zoom_scrollbars is only true on desktop when non-overlay
-    // scrollbars are in use.
-    settings.use_pinch_zoom_scrollbars = true;
+  } else if (settings.use_pinch_virtual_viewport) {
     settings.scrollbar_animator = cc::LayerTreeSettings::LINEAR_FADE;
     settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
   }