Always set damage rect to output rect if 3D context was reshaped.

cc/output/direct_renderer.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/output/direct_renderer.h"
 
 #include <stddef.h>
 
 #include <utility>
 #include <vector>
@@ skipping 249 matching lines @@
       overlay_processor_->GetAndResetOverlayDamage());
   current_frame()->root_damage_rect.Intersect(gfx::Rect(device_viewport_size));
   current_frame()->device_viewport_size = device_viewport_size;
 
   // Only reshape when we know we are going to draw. Otherwise, the reshape
   // can leave the window at the wrong size if we never draw and the proper
   // viewport size is never set.
   bool frame_has_alpha =
       current_frame()->root_render_pass->has_transparent_background;
   bool use_stencil = overdraw_feedback_;
+  bool did_reshape = false;
   if (device_viewport_size != reshape_surface_size_ ||
       device_scale_factor != reshape_device_scale_factor_ ||
       root_render_pass->color_space != reshape_device_color_space_ ||
       frame_has_alpha != reshape_has_alpha_ ||
       use_stencil != reshape_use_stencil_) {
     reshape_surface_size_ = device_viewport_size;
     reshape_device_scale_factor_ = device_scale_factor;
     reshape_device_color_space_ = root_render_pass->color_space;
     reshape_has_alpha_ =
         current_frame()->root_render_pass->has_transparent_background;
     reshape_use_stencil_ = overdraw_feedback_;
     output_surface_->Reshape(
         reshape_surface_size_, reshape_device_scale_factor_,
         reshape_device_color_space_, reshape_has_alpha_, reshape_use_stencil_);
+    did_reshape = true;
   }
 
   BeginDrawingFrame();
 
   for (const auto& pass : *render_passes_in_draw_order) {
     if (!pass->filters.IsEmpty())
       render_pass_filters_[pass->id] = &pass->filters;
     if (!pass->background_filters.IsEmpty())
       render_pass_background_filters_[pass->id] = &pass->background_filters;
   }
@@ skipping 29 matching lines @@
       &current_frame()->root_content_bounds);
   bool was_using_dc_layers = using_dc_layers_;
   if (!current_frame()->dc_layer_overlay_list.empty()) {
     DCHECK(supports_dc_layers_);
     using_dc_layers_ = true;
     frames_since_using_dc_layers_ = 0;
   } else if (++frames_since_using_dc_layers_ >=
              kNumberOfFramesBeforeDisablingDCLayers) {
     using_dc_layers_ = false;
   }
-  if (was_using_dc_layers != using_dc_layers_) {
+  if (supports_dc_layers_ &&
+      (did_reshape || (was_using_dc_layers != using_dc_layers_))) {
+    // The entire surface has to be redrawn if it was reshaped or if switching
+    // from or to DirectComposition layers, because the previous contents are
+    // discarded and some contents would otherwise be undefined.
     current_frame()->root_damage_rect =
         current_frame()->root_render_pass->output_rect;
   }
 
   // We can skip all drawing if the damage rect is now empty.
   bool skip_drawing_root_render_pass =
       current_frame()->root_damage_rect.IsEmpty() && allow_empty_swap_;
 
   // If we have to draw but don't support partial swap, the whole output should
   // be considered damaged.
@@ skipping 296 matching lines @@
 gfx::Size DirectRenderer::RenderPassTextureSize(const RenderPass* render_pass) {
   return render_pass->output_rect.size();
 }
 
 void DirectRenderer::SetCurrentFrameForTesting(const DrawingFrame& frame) {
   current_frame_valid_ = true;
   current_frame_ = frame;
 }
 
 }  // namespace cc