Coalesce damage rects that share an edge.

This fixes the Bloat HTTP page cycler regression, and allows me to remove the
hack I checked in to disable multiple-paints due to an observed DHTML page
cycler regression.

I added a new histogram, RW_IntermediatePaintRectCount, that would have shown
the problem clearly had it been there before.

I included some cleanup in PaintAggregator:
1- rename "r" to "existing_rect" for clarity
2- check for contained (i.e., redundant) invalidates up front

I also changed the opacity of the paint rects used when --show-paint-rects is
specified.  I find myself dogfooding with this command line option enabled, and
I want it to be a little less annoying but still just as useful.

R=brettw
BUG=29477
TEST=none

Review URL: http://codereview.chromium.org/464057

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@33949 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 3 insertions, 9 deletions

diff --git a/chrome/renderer/render_widget.cc b/chrome/renderer/render_widget.cc
index 388dd59..5d56a41 100644
--- a/chrome/renderer/render_widget.cc
+++ b/chrome/renderer/render_widget.cc
@@ -393,7 +393,7 @@ void RenderWidget::PaintDebugBorder(const gfx::Rect& rect,
 
   SkPaint paint;
   paint.setStyle(SkPaint::kStroke_Style);
-  paint.setColor(SkColorSetARGB(0x7F, 0xFF, 0, 0));
+  paint.setColor(SkColorSetARGB(0x3F, 0xFF, 0, 0));
   paint.setStrokeWidth(1);
 
   SkIRect irect;
@@ -484,14 +484,8 @@ void RenderWidget::DoDeferredUpdate() {
     bounds.set_width(canvas->getDevice()->width());
     bounds.set_height(canvas->getDevice()->height());
 
-    HISTOGRAM_COUNTS_100("MPArch.RW_PaintRectCount", update.paint_rects.size());
-
-    // TODO(darin): re-enable painting multiple damage rects once the
-    // page-cycler regressions are resolved.
-    if (update.scroll_rect.IsEmpty()) {
-      update.paint_rects.clear();
-      update.paint_rects.push_back(bounds);
-    }
+    HISTOGRAM_COUNTS_10000("MPArch.RW_PaintRectCount",
+                           update.paint_rects.size());
 
     for (size_t i = 0; i < update.paint_rects.size(); ++i)
       PaintRect(update.paint_rects[i], bounds.origin(), canvas.get());