Clean up flag for out-of-process Viz in Mash

Multi-Process Mash by default runs Viz in Ash process. There is a
--enable-viz flag used to run it as a separate process. This CL changes
that flag to a feature named MashOopViz and adds it to chrome://flags
page. When Viz runs properly as a standalone process, we can get rid of
this flag and make it the default behavior for Mash. Then,
--in-process-gpu flag can be used to run Viz in Ash process.

BUG=862384

Change-Id: I3015a0936a7287e7a7106c86bbed55863eabdbbe
Reviewed-on: https://chromium-review.googlesource.com/c/1349478Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Mohsen Izadi <mohsen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611985}

chrome/browser/about_flags.cc

@@ -1693,6 +1693,9 @@ const FeatureEntry kFeatureEntries[] = {
     {"mash", flag_descriptions::kUseMashName,
      flag_descriptions::kUseMashDescription, kOsCrOS,
      FEATURE_VALUE_TYPE(features::kMash)},
+    {"mash-oop-viz", flag_descriptions::kMashOopVizName,
+     flag_descriptions::kMashOopVizDescription, kOsCrOS,
+     FEATURE_VALUE_TYPE(features::kMashOopViz)},
     {"newblue", flag_descriptions::kNewblueName,
      flag_descriptions::kNewblueDescription, kOsCrOS,
      FEATURE_VALUE_TYPE(device::kNewblueDaemon)},

chrome/browser/flag-metadata.json

@@ -2399,6 +2399,11 @@
     "owners": [ "mustash-team@google.com" ],
     "expiry_milestone": 79
   },
+  {
+    "name": "mash-oop-viz",
+    "owners": [ "mustash-team@google.com" ],
+    "expiry_milestone": 74
+  },
   {
     "name": "material-design-ink-drop-animation-speed",
     // "owners": [ "your-team" ],

chrome/browser/flag_descriptions.cc

@@ -3470,6 +3470,11 @@ const char kLockScreenNotificationName[] = "Lock screen notification";
 const char kLockScreenNotificationDescription[] =
     "Enable notifications on the lock screen.";
 
+const char kMashOopVizName[] = "Out-of-process viz for mash";
+const char kMashOopVizDescription[] =
+    "Runs viz in a separate process when mash is enabled (otherwise viz would "
+    "run in ash process)";
+
 const char kMaterialDesignInkDropAnimationSpeedName[] =
     "Material design ink drop animation speed";
 const char kMaterialDesignInkDropAnimationSpeedDescription[] =

chrome/browser/flag_descriptions.h

@@ -2090,6 +2090,9 @@ extern const char kImeServiceDescription[];
 extern const char kLockScreenNotificationName[];
 extern const char kLockScreenNotificationDescription[];
 
+extern const char kMashOopVizName[];
+extern const char kMashOopVizDescription[];
+
 extern const char kMaterialDesignInkDropAnimationSpeedName[];
 extern const char kMaterialDesignInkDropAnimationSpeedDescription[];
 extern const char kMaterialDesignInkDropAnimationFast[];

services/ws/gpu_host/gpu_host.cc

@@ -26,6 +26,7 @@
 #include "services/viz/privileged/interfaces/viz_main.mojom.h"
 #include "services/viz/public/interfaces/constants.mojom.h"
 #include "services/ws/gpu_host/gpu_host_delegate.h"
+#include "ui/base/ui_base_features.h"
 #include "ui/gfx/buffer_format_util.h"
 
 #if defined(OS_WIN)
@@ -44,12 +45,6 @@ namespace {
 // The client Id 1 is reserved for the frame sink manager.
 const int32_t kInternalGpuChannelClientId = 2;
 
-// TODO(crbug.com/620927): This should be removed once ozone-mojo is done.
-bool HasSplitVizProcess() {
-  constexpr char kEnableViz[] = "enable-viz";
-  return base::CommandLine::ForCurrentProcess()->HasSwitch(kEnableViz);
-}
-
 class GpuClientDelegate : public viz::GpuClientDelegate {
  public:
   GpuClientDelegate(viz::GpuHostImpl* gpu_host_impl,
@@ -100,7 +95,7 @@ GpuHost::GpuHost(GpuHostDelegate* delegate,
   viz::GpuHostImpl::InitFontRenderParams(
       gfx::GetFontRenderParams(gfx::FontRenderParamsQuery(), nullptr));
 
-  bool in_process = !connector || !HasSplitVizProcess();
+  bool in_process = !connector || !features::IsMashOopVizEnabled();
 
   viz::mojom::VizMainPtr viz_main_ptr;
   if (in_process) {

tools/metrics/histograms/enums.xml

@@ -30051,6 +30051,7 @@ from previous Chrome versions.
       label="AutofillSaveCardDialogUnlabeledExpirationDate:disabled"/>
   <int value="-697751423" label="disable-quickoffice-component-app"/>
   <int value="-696693295" label="Canvas2DImageChromium:disabled"/>
+  <int value="-694187898" label="MashOopViz:disabled"/>
   <int value="-684900739" label="disable-merge-key-char-events"/>
   <int value="-684223908" label="enable-android-wallpapers-app"/>
   <int value="-683370370" label="EnableAppDataSearch:enabled"/>
@@ -31285,6 +31286,7 @@ from previous Chrome versions.
   <int value="1614596813" label="CloseButtonsInactiveTabs:disabled"/>
   <int value="1615988672" label="GrantNotificationsToDSE:enabled"/>
   <int value="1617187093" label="enable-improved-a2hs"/>
+  <int value="1618633341" label="MashOopViz:enabled"/>
   <int value="1621298798" label="VrBrowserKeyboard:enabled"/>
   <int value="1622131033" label="ozone-test-single-overlay-support"/>
   <int value="1626824478" label="ExperimentalAppBanners:disabled"/>

ui/base/ui_base_features.cc

@@ -143,6 +143,9 @@ const base::Feature kDirectManipulationStylus = {
 
 const base::Feature kMash = {"Mash", base::FEATURE_DISABLED_BY_DEFAULT};
 
+const base::Feature kMashOopViz = {"MashOopViz",
+                                   base::FEATURE_DISABLED_BY_DEFAULT};
+
 const base::Feature kSingleProcessMash = {"SingleProcessMash",
                                           base::FEATURE_DISABLED_BY_DEFAULT};
 
@@ -154,6 +157,10 @@ bool IsMultiProcessMash() {
   return base::FeatureList::IsEnabled(features::kMash);
 }
 
+bool IsMashOopVizEnabled() {
+  return base::FeatureList::IsEnabled(features::kMashOopViz);
+}
+
 bool IsSingleProcessMash() {
   return base::FeatureList::IsEnabled(features::kSingleProcessMash);
 }

ui/base/ui_base_features.h

@@ -57,6 +57,12 @@ UI_BASE_EXPORT extern const base::Feature kDirectManipulationStylus;
 // TODO(jamescook): Make flag only available in Chrome OS.
 UI_BASE_EXPORT extern const base::Feature kMash;
 
+// Used to run Viz in its own process when kMash is enabled. Viz is run in Ash
+// process by default.
+// TODO(mohsen): Remove this when Viz can run fully in a separate process. Then
+// make it the default kMash behavior.
+UI_BASE_EXPORT extern const base::Feature kMashOopViz;
+
 UI_BASE_EXPORT extern const base::Feature kSingleProcessMash;
 
 // Returns true if Chrome's aura usage is backed by the WindowService.
@@ -66,6 +72,8 @@ UI_BASE_EXPORT bool IsUsingWindowService();
 // service and Viz graphics). See //ash/README.md.
 UI_BASE_EXPORT bool IsMultiProcessMash();
 
+UI_BASE_EXPORT bool IsMashOopVizEnabled();
+
 // Returns true if code outside of ash is using the WindowService. In this mode
 // there are two aura::Envs. Ash uses one with Env::Mode::LOCAL. Non-ash code
 // uses an aura::Env with a mode of MUS. The non-ash code using mus targets the