Initial implementation for sharing field trial state (win)

content/browser/gpu/gpu_process_host.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/gpu/gpu_process_host.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <list>
@@ skipping 30 matching lines @@
 #include "content/common/mojo/mojo_child_connection.h"
 #include "content/common/view_messages.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/content_browser_client.h"
 #include "content/public/browser/gpu_utils.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/render_widget_host_view_frame_subscriber.h"
 #include "content/public/common/connection_filter.h"
 #include "content/public/common/content_client.h"
+#include "content/public/common/content_features.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/mojo_channel_switches.h"
 #include "content/public/common/mojo_shell_connection.h"
 #include "content/public/common/result_codes.h"
 #include "content/public/common/sandbox_type.h"
 #include "content/public/common/sandboxed_process_launcher_delegate.h"
 #include "content/public/common/service_names.h"
 #include "gpu/command_buffer/service/gpu_preferences.h"
 #include "gpu/command_buffer/service/gpu_switches.h"
 #include "gpu/ipc/service/switches.h"
@@ skipping 905 matching lines @@
 #else
   int child_flags = ChildProcessHost::CHILD_NORMAL;
 #endif
 
   base::FilePath exe_path = ChildProcessHost::GetChildPath(child_flags);
   if (exe_path.empty())
     return false;
 
   base::CommandLine* cmd_line = new base::CommandLine(exe_path);
 #endif
+
   cmd_line->AppendSwitchASCII(switches::kProcessType, switches::kGpuProcess);
-  BrowserChildProcessHostImpl::CopyFeatureAndFieldTrialFlags(cmd_line);
+
+#if defined(OS_WIN)
+  if (base::FeatureList::IsEnabled(
+          features::kShareFieldTrialStateViaSharedMemory))

[Alexei Svitkine (slow), 2016/10/04 18:49:35]

Nit: {}'s

[lawrencewu, 2016/10/05 20:57:56]

Done.

+    field_trial_state_.reset(new base::SharedMemory());
+#endif
+  BrowserChildProcessHostImpl::CopyFeatureAndFieldTrialFlags(
+      cmd_line, field_trial_state_.get());
+#if defined(OS_WIN)
+  if (!field_trial_state_.get()->handle().GetHandle())

[Alexei Svitkine (slow), 2016/10/04 18:49:36]

Is this just an error case? Needs a comment at the very least.

[lawrencewu, 2016/10/05 20:57:56]

Yes, it is the case when there were no field trials (happens in browsertests).
The handle will still try to get passed down but won't work because it's
invalid. With the new changes we don't need to do this anymore, it's implicit in
the flow.

+    field_trial_state_.reset();
+#endif
 
 #if defined(OS_WIN)
   cmd_line->AppendArg(switches::kPrefetchArgumentGpu);
 #endif  // defined(OS_WIN)
 
   if (kind_ == GPU_PROCESS_KIND_UNSANDBOXED)
     cmd_line->AppendSwitch(switches::kDisableGpuSandbox);
 
   // TODO(penghuang): Replace all GPU related switches with GpuPreferences.
   // https://crbug.com/590825
@@ skipping 23 matching lines @@
   }
 
   UMA_HISTOGRAM_BOOLEAN("GPU.GPUProcessSoftwareRendering",
                         swiftshader_rendering_);
 
   // If specified, prepend a launcher program to the command line.
   if (!gpu_launcher.empty())
     cmd_line->PrependWrapper(gpu_launcher);
 
   process_->Launch(
-      new GpuSandboxedProcessLauncherDelegate(cmd_line,
-                                              process_->GetHost()),
-      cmd_line,
-      true);
+      new GpuSandboxedProcessLauncherDelegate(cmd_line, process_->GetHost()),
+      cmd_line, field_trial_state_.get(), true);
   process_launched_ = true;
 
   UMA_HISTOGRAM_ENUMERATION("GPU.GPUProcessLifetimeEvents",
                             LAUNCHED, GPU_PROCESS_LIFETIME_EVENT_MAX);
   return true;
 }
 
 void GpuProcessHost::SendOutstandingReplies() {
   valid_ = false;
   // First send empty channel handles for all EstablishChannel requests.
@@ skipping 132 matching lines @@
   TRACE_EVENT0("gpu", "GpuProcessHost::OnCacheShader");
   ClientIdToShaderCacheMap::iterator iter =
       client_id_to_shader_cache_.find(client_id);
   // If the cache doesn't exist then this is an off the record profile.
   if (iter == client_id_to_shader_cache_.end())
     return;
   iter->second->Cache(GetShaderPrefixKey() + ":" + key, shader);
 }
 
 }  // namespace content