Adds CupsProxyService chrome flag

DDoc: go/cups-plugin

Adds flag to condition above printing pipeline on. Will be used to
condition the CupsProxyService startup.

Bug: chromium:495409
Test: build unit_tests & run CheckHistograms + EveryFlagHasMetadata
Change-Id: Id4b75ceca33a9930992e1732537621cbc154a64b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1601835
Reviewed-by: Lei Zhang <[email protected]>
Reviewed-by: Sean Kau <[email protected]>
Commit-Queue: Luum Habtemariam <[email protected]>
Cr-Commit-Position: refs/heads/master@{#658334}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 5531dc5..0725d8c 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -3197,6 +3197,9 @@
     {"enable-arc-cups-api", flag_descriptions::kArcCupsApiName,
      flag_descriptions::kArcCupsApiDescription, kOsCrOS,
      FEATURE_VALUE_TYPE(features::kArcCupsApi)},
+    {"enable-cros-vm-cups-proxy", flag_descriptions::kCrosVmCupsProxyName,
+     flag_descriptions::kCrosVmCupsProxyDescription, kOsCrOS,
+     FEATURE_VALUE_TYPE(features::kCrosVmCupsProxy)},
 #endif  // OS_CHROMEOS
 
 #if defined(OS_CHROMEOS)