chromeos: enable ozone platform headless on CrOS

IsRunningAsSystemCompositor must return false, because input
should be disabled on ozone platform headless.

BUG=b:160309778
TEST=manual

Change-Id: I8a97b166b42a581a275c305355f0c4434e5adbbd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2276426Reviewed-by: Michael Spang <spang@chromium.org>
Reviewed-by: Denis Kuznetsov [CET] <antrim@chromium.org>
Commit-Queue: Polina Bondarenko <pbond@chromium.org>
Auto-Submit: Polina Bondarenko <pbond@chromium.org>
Cr-Commit-Position: refs/heads/master@{#786271}

chromeos/system/BUILD.gn

@@ -11,6 +11,7 @@ component("system") {
     "//base",
     "//chromeos:chromeos_export",
     "//chromeos/constants",
+    "//ui/ozone:ozone_base",
   ]
   sources = [
     "core_scheduling.cc",

chromeos/system/DEPS

+include_rules = [
+  "+ui/ozone/public"
+]

chromeos/system/devicemode.cc

@@ -7,10 +7,15 @@
 #include "base/command_line.h"
 #include "base/system/sys_info.h"
 #include "chromeos/constants/chromeos_switches.h"
+#include "ui/ozone/public/ozone_switches.h"
 
 namespace chromeos {
 
 bool IsRunningAsSystemCompositor() {
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          ::switches::kDisableRunningAsSystemCompositor)) {
+    return false;
+  }
   static bool is_running_on_chrome_os = base::SysInfo::IsRunningOnChromeOS();
   return is_running_on_chrome_os ||
          base::CommandLine::ForCurrentProcess()->HasSwitch(

ui/ozone/BUILD.gn

@@ -129,6 +129,7 @@ jumbo_component("ozone_base") {
   visibility += [
     # Everyone should depend on //ui/ozone instead except a handful of
     # things that would otherwise create a cycle.
+    "//chromeos/system:system",
     "//ui/events/ozone/*",
     "//ui/ozone/common/*",
     "//ui/ozone/public/mojom",

ui/ozone/platform/headless/ozone_platform_headless.cc

@@ -138,6 +138,7 @@ OzonePlatform* CreateOzonePlatformHeadless() {
   base::FilePath location;
   if (cmd->HasSwitch(switches::kOzoneDumpFile))
     location = cmd->GetSwitchValuePath(switches::kOzoneDumpFile);
+  cmd->AppendSwitch(switches::kDisableRunningAsSystemCompositor);
   return new OzonePlatformHeadless(location);
 }
 

ui/ozone/public/ozone_switches.cc

@@ -18,4 +18,8 @@ const char kEnableWaylandIme[] = "enable-wayland-ime";
 // Disable explicit DMA-fences
 const char kDisableExplicitDmaFences[] = "disable-explicit-dma-fences";
 
+// Disable running as system compositor.
+const char kDisableRunningAsSystemCompositor[] =
+    "disable-running-as-system-compositor";
+
 }  // namespace switches

ui/ozone/public/ozone_switches.h

@@ -18,6 +18,9 @@ COMPONENT_EXPORT(OZONE_BASE) extern const char kEnableWaylandIme[];
 
 COMPONENT_EXPORT(OZONE_BASE) extern const char kDisableExplicitDmaFences[];
 
+COMPONENT_EXPORT(OZONE_BASE)
+extern const char kDisableRunningAsSystemCompositor[];
+
 }  // namespace switches
 
 #endif  // UI_OZONE_PUBLIC_OZONE_SWITCHES_H_