cc: Implement overdraw feedback debugging feature.

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 <unordered_map>
 #include <utility>
 #include <vector>
 
+#include "base/auto_reset.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/trace_event/trace_event.h"
 #include "cc/base/math_util.h"
 #include "cc/output/bsp_tree.h"
 #include "cc/output/bsp_walk_action.h"
 #include "cc/output/copy_output_request.h"
 #include "cc/output/renderer_settings.h"
 #include "cc/quads/draw_quad.h"
 #include "cc/resources/scoped_resource.h"
@@ skipping 195 matching lines @@
                                const gfx::Size& device_viewport_size) {
   DCHECK(visible_);
   TRACE_EVENT0("cc", "DirectRenderer::DrawFrame");
   UMA_HISTOGRAM_COUNTS(
       "Renderer4.renderPassCount",
       base::saturated_cast<int>(render_passes_in_draw_order->size()));
 
   RenderPass* root_render_pass = render_passes_in_draw_order->back().get();
   DCHECK(root_render_pass);
 
+  bool overdraw_tracing_enabled;
+  TRACE_EVENT_CATEGORY_GROUP_ENABLED(
+      TRACE_DISABLED_BY_DEFAULT("cc.debug.overdraw"),
+      &overdraw_tracing_enabled);
+  bool overdraw_feedback =
+      settings_->show_overdraw_feedback || overdraw_tracing_enabled;
+  if (overdraw_feedback && !output_surface_->capabilities().supports_stencil) {
+#if DCHECK_IS_ON()
+    DLOG_IF(WARNING, !overdraw_feedback_support_missing_logged_once_)
+        << "Overdraw feedback enabled on platform without support.";
+    overdraw_feedback_support_missing_logged_once_ = true;
+#endif
+    overdraw_feedback = false;
+  }
+  base::AutoReset<bool> auto_reset_overdraw_feedback(&overdraw_feedback_,
+                                                     overdraw_feedback);
+
   DrawingFrame frame;
   frame.render_passes_in_draw_order = render_passes_in_draw_order;
   frame.root_render_pass = root_render_pass;
   frame.root_damage_rect = root_render_pass->damage_rect;
   frame.root_damage_rect.Union(overlay_processor_->GetAndResetOverlayDamage());
   frame.root_damage_rect.Intersect(gfx::Rect(device_viewport_size));
   frame.device_viewport_size = device_viewport_size;
   frame.device_color_space = device_color_space;
 
   // 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 = frame.root_render_pass->has_transparent_background;
+  bool use_stencil = overdraw_feedback_;
   if (device_viewport_size != reshape_surface_size_ ||
       device_scale_factor != reshape_device_scale_factor_ ||
       device_color_space != reshape_device_color_space_ ||
-      frame_has_alpha != reshape_has_alpha_) {
+      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_ = device_color_space;
     reshape_has_alpha_ = frame.root_render_pass->has_transparent_background;
-    output_surface_->Reshape(reshape_surface_size_,
-                             reshape_device_scale_factor_,
-                             reshape_device_color_space_, reshape_has_alpha_);
+    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_);
   }
 
   BeginDrawingFrame(&frame);
 
   for (const auto& pass : *render_passes_in_draw_order) {
     if (!pass->filters.IsEmpty())
       render_pass_filters_.push_back(std::make_pair(pass->id, &pass->filters));
     if (!pass->background_filters.IsEmpty()) {
       render_pass_background_filters_.push_back(
           std::make_pair(pass->id, &pass->background_filters));
@@ skipping 346 matching lines @@
   auto iter = render_pass_textures_.find(render_pass_id);
   return iter != render_pass_textures_.end() && iter->second->id();
 }
 
 // static
 gfx::Size DirectRenderer::RenderPassTextureSize(const RenderPass* render_pass) {
   return render_pass->output_rect.size();
 }
 
 }  // namespace cc