Revert 255481 "Remove --ui-prioritize-in-gpu-process"

Reverting to see whether this introduced flakiness in the WebGL conformance
tests on the Win GPU bots. If it did, that means this CL exposed a
preexisting race condition. See Issue 350572.

> Remove --ui-prioritize-in-gpu-process
> 
> It is already always on on Android and Chrome OS. Consensus is that we should
> turn on on all Aura platform. The flag is a noop on other platforms.
> 
> BUG=344083
> 
> Review URL: https://codereview.chromium.org/183883023

TBR=piman@chromium.org
BUG=344083,350572

Review URL: https://codereview.chromium.org/189373012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255722 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/chromeos/login/chrome_restart_request.cc

@@ -129,6 +129,7 @@ std::string DeriveCommandLine(const GURL& start_url,
       ::switches::kTouchEvents,
       ::switches::kTouchOptimizedUI,
       ::switches::kUIDisableThreadedCompositing,
+      ::switches::kUIPrioritizeInGpuProcess,
 #if defined(USE_CRAS)
       ::switches::kUseCras,
 #endif

content/browser/android/content_startup_flags.cc

@@ -89,6 +89,8 @@ void SetContentCommandLineFlags(int max_render_process_count,
   parsed_command_line->AppendSwitch(
       cc::switches::kDisableCompositedAntialiasing);
 
+  parsed_command_line->AppendSwitch(switches::kUIPrioritizeInGpuProcess);
+
   parsed_command_line->AppendSwitch(switches::kEnableDelegatedRenderer);
 
   if (!plugin_descriptor.empty()) {

content/browser/gpu/gpu_process_host.cc

@@ -1105,6 +1105,9 @@ bool GpuProcessHost::LaunchGpuProcess(const std::string& channel_id) {
 #if defined(OS_CHROMEOS)
     chromeos::switches::kGpuSandboxFailuresNonfatal,
 #endif
+#if defined(USE_AURA)
+    switches::kUIPrioritizeInGpuProcess,
+#endif
 #if defined(USE_OZONE)
     switches::kOzonePlatform,
 #endif

content/common/gpu/image_transport_surface_android.cc

@@ -92,8 +92,11 @@ bool ImageTransportSurfaceAndroid::Initialize() {
 
   GpuChannel* parent_channel =
       GetHelper()->manager()->LookupChannel(parent_client_id_);
-  if (parent_channel)
-    GetHelper()->SetPreemptByFlag(parent_channel->GetPreemptionFlag());
+  if (parent_channel) {
+    const CommandLine* command_line = CommandLine::ForCurrentProcess();
+    if (command_line->HasSwitch(switches::kUIPrioritizeInGpuProcess))
+      GetHelper()->SetPreemptByFlag(parent_channel->GetPreemptionFlag());
+  }
 
   return true;
 }

content/common/gpu/texture_image_transport_surface.cc

@@ -73,8 +73,11 @@ bool TextureImageTransportSurface::Initialize() {
     return false;
 
   GpuChannel* parent_channel = manager->LookupChannel(handle_.parent_client_id);
-  if (parent_channel)
-    helper_->SetPreemptByFlag(parent_channel->GetPreemptionFlag());
+  if (parent_channel) {
+    const CommandLine* command_line = CommandLine::ForCurrentProcess();
+    if (command_line->HasSwitch(switches::kUIPrioritizeInGpuProcess))
+      helper_->SetPreemptByFlag(parent_channel->GetPreemptionFlag());
+  }
 
   return true;
 }

content/public/common/content_switches.cc

@@ -898,6 +898,12 @@ const char kTraceStartupDuration[]          = "trace-startup-duration";
 // all events since startup.
 const char kTraceStartupFile[]              = "trace-startup-file";
 
+
+
+// Prioritizes the UI's command stream in the GPU process
+extern const char kUIPrioritizeInGpuProcess[] =
+    "ui-prioritize-in-gpu-process";
+
 // Overrides the preferred discardable memory implementation.
 const char kUseDiscardableMemory[] = "use-discardable-memory";
 

content/public/common/content_switches.h

@@ -252,6 +252,7 @@ extern const char kTraceShutdownFile[];
 extern const char kTraceStartup[];
 extern const char kTraceStartupDuration[];
 extern const char kTraceStartupFile[];
+CONTENT_EXPORT extern const char kUIPrioritizeInGpuProcess[];
 CONTENT_EXPORT extern const char kUseDiscardableMemory[];
 CONTENT_EXPORT extern const char kUseFakeDeviceForMediaStream[];
 CONTENT_EXPORT extern const char kUseFakeUIForMediaStream[];