chromeos: Add SingleProcessMash feature to about:flags

This will let us more easily test on canary channel Chromebooks.

Bug: none
Change-Id: Ie382991d547f0e48d8198fc4037580033a9dfb3a
Reviewed-on: https://chromium-review.googlesource.com/1211880Reviewed-by: Jun Mukai <mukai@chromium.org>
Commit-Queue: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589629}

chrome/browser/about_flags.cc

@@ -1765,6 +1765,9 @@ const FeatureEntry kFeatureEntries[] = {
     {"show-touch-hud", flag_descriptions::kShowTouchHudName,
      flag_descriptions::kShowTouchHudDescription, kOsCrOS,
      SINGLE_VALUE_TYPE(ash::switches::kAshTouchHud)},
+    {"single-process-mash", flag_descriptions::kSingleProcessMashName,
+     flag_descriptions::kSingleProcessMashDescription, kOsCrOS,
+     FEATURE_VALUE_TYPE(features::kSingleProcessMash)},
 #endif  // OS_CHROMEOS
     {
         "disable-accelerated-video-decode",

chrome/browser/flag_descriptions.cc

@@ -3465,6 +3465,12 @@ const char kShowTouchHudDescription[] =
     "Ctrl-Alt-I shows a heads-up display view in the top-left corner. Helps "
     "debug hardware issues that generate spurious touch events.";
 
+const char kSingleProcessMashName[] =
+    "In-process window service (SingleProcessMash)";
+const char kSingleProcessMashDescription[] =
+    "Runs the system UI (ash) as a mojo service, but inside the browser "
+    "process. The browser uses the mojo window service (ws) APIs.";
+
 const char kSlideTopChromeWithPageScrollsName[] =
     "Slide top-chrome with page scrolls";
 const char kSlideTopChromeWithPageScrollsDescription[] =

chrome/browser/flag_descriptions.h

@@ -2111,6 +2111,9 @@ extern const char kShowTapsDescription[];
 extern const char kShowTouchHudName[];
 extern const char kShowTouchHudDescription[];
 
+extern const char kSingleProcessMashName[];
+extern const char kSingleProcessMashDescription[];
+
 extern const char kSlideTopChromeWithPageScrollsName[];
 extern const char kSlideTopChromeWithPageScrollsDescription[];
 

tools/metrics/histograms/enums.xml

@@ -28516,6 +28516,7 @@ from previous Chrome versions.
   <int value="-1357778876" label="ExplicitLanguageAsk:enabled"/>
   <int value="-1357655121" label="enable-iframe-based-signin"/>
   <int value="-1357008397" label="ContextualSuggestionsCarousel:disabled"/>
+  <int value="-1351968795" label="SingleProcessMash:enabled"/>
   <int value="-1351328710"
       label="OmniboxUIExperimentJogTextfieldOnPopup:disabled"/>
   <int value="-1349896789" label="DelayNavigation:enabled"/>
@@ -30223,6 +30224,7 @@ from previous Chrome versions.
   <int value="2071229145" label="BloatedRendererDetection:enabled"/>
   <int value="2071340353" label="progress-bar-completion"/>
   <int value="2071461362" label="disable-credit-card-scan"/>
+  <int value="2072231406" label="SingleProcessMash:disabled"/>
   <int value="2075207488" label="AutomaticPasswordGeneration:disabled"/>
   <int value="2076787478" label="OmniboxDisplayTitleForCurrentUrl:disabled"/>
   <int value="2076903744" label="progress-bar-animation"/>