Add slimming paint v2 command line switch and pref

(Requires blink change https://codereview.chromium.org/1277313002/)

R=chrishtr,jam
TBR=mkwst (a message field to pass the new pref)

Review URL: https://codereview.chromium.org/1284483002

Cr-Commit-Position: refs/heads/master@{#342648}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 5e3e70b..8abc997 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -827,6 +827,11 @@
      IDS_FLAGS_ENABLE_SLIMMING_PAINT_DESCRIPTION,
      kOsAll,
      SINGLE_VALUE_TYPE(switches::kEnableSlimmingPaint)},
+     {"enable-slimming-paint-v2",
+      IDS_FLAGS_ENABLE_SLIMMING_PAINT_V2_NAME,
+      IDS_FLAGS_ENABLE_SLIMMING_PAINT_V2_DESCRIPTION,
+      kOsAll,
+      SINGLE_VALUE_TYPE(switches::kEnableSlimmingPaintV2)},
     {"enable-experimental-web-platform-features",
      IDS_FLAGS_EXPERIMENTAL_WEB_PLATFORM_FEATURES_NAME,
      IDS_FLAGS_EXPERIMENTAL_WEB_PLATFORM_FEATURES_DESCRIPTION,