Remove implementation for obsoleted metrics

Metrics Compositing.Display.Draw.Occlusion.Drawing.Area.Saved2.* and
Compositing.Display.Draw.Occlusion.Percentage.Saved.* are expired after
M77. Remove the implementation in display.cc.

Bug: 995633, 993176, 960184
Change-Id: Id1658ecfad7518f7b36fbb599191c422d0de96c5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1900351Reviewed-by: danakj <danakj@chromium.org>
Commit-Queue: Yi Xu <yiyix@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713079}

components/viz/service/display/display.cc

@@ -9,12 +9,10 @@
 
 #include "base/debug/dump_without_crashing.h"
 #include "base/metrics/histogram_macros.h"
-#include "base/numerics/checked_math.h"
 #include "base/optional.h"
 #include "base/timer/elapsed_timer.h"
 #include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
-#include "cc/base/math_util.h"
 #include "cc/base/simple_enclosed_region.h"
 #include "cc/benchmarks/benchmark_instrumentation.h"
 #include "components/viz/common/display/renderer_settings.h"
@@ -863,39 +861,22 @@ void Display::RemoveOverdrawQuads(CompositorFrame* frame) {
   int minimum_draw_occlusion_width =
       settings_.kMinimumDrawOcclusionSize.width() * device_scale_factor_;
 
-  // Total quad area to be drawn on screen before applying draw occlusion.
-  base::CheckedNumeric<uint64_t> total_quad_area_shown_wo_occlusion_px = 0;
-
-  // Total area not draw skipped by draw occlusion.
-  base::CheckedNumeric<uint64_t> total_area_saved_in_px = 0;
-
   for (const auto& pass : frame->render_pass_list) {
     // TODO(yiyix): Add filter effects to draw occlusion calculation and perform
     // draw occlusion on render pass.
     if (!pass->filters.IsEmpty() || !pass->backdrop_filters.IsEmpty()) {
-      for (auto* const quad : pass->quad_list) {
-        total_quad_area_shown_wo_occlusion_px +=
-            quad->visible_rect.size().GetCheckedArea();
-      }
       continue;
     }
 
     // TODO(yiyix): Perform draw occlusion inside the render pass with
     // transparent background.
     if (pass != frame->render_pass_list.back()) {
-      for (auto* const quad : pass->quad_list) {
-        total_quad_area_shown_wo_occlusion_px +=
-            quad->visible_rect.size().GetCheckedArea();
-      }
       continue;
     }
 
     auto quad_list_end = pass->quad_list.end();
     gfx::Rect occlusion_in_quad_content_space;
     for (auto quad = pass->quad_list.begin(); quad != quad_list_end;) {
-      total_quad_area_shown_wo_occlusion_px +=
-          quad->visible_rect.size().GetCheckedArea();
-
       // Skip quad if it is a RenderPassDrawQuad because RenderPassDrawQuad is a
       // special type of DrawQuad where the visible_rect of shared quad state is
       // not entirely covered by draw quads in it; or the DrawQuad size is
@@ -983,7 +964,6 @@ void Display::RemoveOverdrawQuads(CompositorFrame* frame) {
         // Case 1: for simple transforms (scale or translation), define the
         // occlusion region in the quad content space. If the |quad| is not
         // shown on the screen, then remove |quad| from the compositor frame.
-        total_area_saved_in_px += quad->visible_rect.size().GetCheckedArea();
         quad = pass->quad_list.EraseAndInvalidateAllPointers(quad);
 
       } else if (occlusion_in_quad_content_space.Intersects(
@@ -995,7 +975,6 @@ void Display::RemoveOverdrawQuads(CompositorFrame* frame) {
         quad->visible_rect.Subtract(occlusion_in_quad_content_space);
         if (origin_rect != quad->visible_rect) {
           origin_rect.Subtract(quad->visible_rect);
-          total_area_saved_in_px += origin_rect.size().GetCheckedArea();
         }
         ++quad;
       } else if (occlusion_in_quad_content_space.IsEmpty() &&
@@ -1005,26 +984,12 @@ void Display::RemoveOverdrawQuads(CompositorFrame* frame) {
         // Case 3: for non simple transforms, define the occlusion region in
         // target space. If the |quad| is not shown on the screen, then remove
         // |quad| from the compositor frame.
-        total_area_saved_in_px += quad->visible_rect.size().GetCheckedArea();
         quad = pass->quad_list.EraseAndInvalidateAllPointers(quad);
       } else {
         ++quad;
       }
     }
   }
-
-  UMA_HISTOGRAM_PERCENTAGE(
-      "Compositing.Display.Draw.Occlusion.Percentage.Saved",
-      total_quad_area_shown_wo_occlusion_px.ValueOrDefault(0) == 0
-          ? 0
-          : static_cast<uint64_t>(total_area_saved_in_px.ValueOrDie()) * 100 /
-                static_cast<uint64_t>(
-                    total_quad_area_shown_wo_occlusion_px.ValueOrDie()));
-
-  UMA_HISTOGRAM_COUNTS_1M(
-      "Compositing.Display.Draw.Occlusion.Drawing.Area.Saved2",
-      static_cast<uint64_t>(total_area_saved_in_px.ValueOrDefault(
-          std::numeric_limits<uint64_t>::max())));
 }
 
 void Display::RunDrawCallbacks() {