[SP] Enable Slimming Paint by default in Chromium and Blink.

content/shell/renderer/layout_test/blink_test_runner.cc

 // Copyright (c) 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 "content/shell/renderer/layout_test/blink_test_runner.h"
 
 #include <algorithm>
 #include <clocale>
 #include <cmath>
 
@@ skipping 782 matching lines @@
     if (test_config_.enable_pixel_dumping &&
         interfaces->TestRunner()->ShouldGeneratePixelResults()) {
       CHECK(render_view()->GetWebView()->isAcceleratedCompositingActive());
       proxy()->CapturePixelsAsync(base::Bind(
           &BlinkTestRunner::CaptureDumpPixels, base::Unretained(this)));
       return;
     }
   }
 
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kEnableSlimmingPaint)) {
+          switches::kEnableSlimmingPaint) ||
+      !base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kDisableSlimmingPaint)) {
       // Force a layout/paint by the end of the test to ensure test coverage of
       // incremental painting in slimming paint mode.
       proxy()->LayoutAndPaintAsyncThen(base::Bind(
           &BlinkTestRunner::CaptureDumpComplete, base::Unretained(this)));
       return;
   }
 
   CaptureDumpComplete();
 }
 
@@ skipping 81 matching lines @@
 
   leak_detector_->TryLeakDetection(main_frame);
 }
 
 void BlinkTestRunner::ReportLeakDetectionResult(
     const LeakDetectionResult& report) {
   Send(new ShellViewHostMsg_LeakDetectionDone(routing_id(), report));
 }
 
 }  // namespace content