Add trial for DirectWrite, and reorder some initialization so it can take effect

content/common/sandbox_win.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/common/sandbox_win.h"
 
 #include <string>
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/debug/profiler.h"
 #include "base/debug/trace_event.h"
 #include "base/file_util.h"
 #include "base/hash.h"
+#include "base/metrics/field_trial.h"
 #include "base/path_service.h"
 #include "base/process/launch.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/win/iat_patch_function.h"
 #include "base/win/scoped_handle.h"
 #include "base/win/scoped_process_information.h"
 #include "base/win/windows_version.h"
 #include "content/public/common/content_client.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/sandbox_init.h"
 #include "content/public/common/sandboxed_process_launcher_delegate.h"
 #include "sandbox/win/src/process_mitigations.h"
 #include "sandbox/win/src/sandbox.h"
 #include "sandbox/win/src/sandbox_nt_util.h"
 #include "sandbox/win/src/win_utils.h"
+#include "ui/gfx/win/dpi.h"
 
 static sandbox::BrokerServices* g_broker_services = NULL;
 static sandbox::TargetServices* g_target_services = NULL;
 
 namespace content {
 namespace {
 
 // The DLLs listed here are known (or under strong suspicion) of causing crashes
 // when they are loaded in the renderer. Note: at runtime we generate short
 // versions of the dll name only if the dll has an extension.
@@ skipping 518 matching lines @@
   sandbox::ResultCode result = target_services->Init();
   g_target_services = target_services;
   return sandbox::SBOX_ALL_OK == result;
 }
 
 bool ShouldUseDirectWrite() {
   // If the flag is currently on, and we're on Win7 or above, we enable
   // DirectWrite. Skia does not require the additions to DirectWrite in QFE
   // 2670838, so a Win7 check is sufficient. We do not currently attempt to
   // support Vista, where SP2 and the Platform Update are required.
+  if (base::win::GetVersion() < base::win::VERSION_WIN7)
+    return false;
+
+  // If forced off, don't use it.
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
-  return !command_line.HasSwitch(switches::kDisableDirectWrite) &&
-         base::win::GetVersion() >= base::win::VERSION_WIN7;
+  if (command_line.HasSwitch(switches::kDisableDirectWrite))
+    return false;
+
+  // Can't use GDI on HiDPI.
+  if (gfx::GetDPIScale() > 1.0f)
+    return true;
+
+  // Otherwise, Finch.
+  const std::string group_name =
+      base::FieldTrialList::FindFullName("DirectWrite");
+  return group_name == "Enabled";
 }
 
 base::ProcessHandle StartSandboxedProcess(
     SandboxedProcessLauncherDelegate* delegate,
     CommandLine* cmd_line) {
   const CommandLine& browser_command_line = *CommandLine::ForCurrentProcess();
   std::string type_str = cmd_line->GetSwitchValueASCII(switches::kProcessType);
 
   TRACE_EVENT_BEGIN_ETW("StartProcessWithAccess", 0, type_str);
 
@@ skipping 167 matching lines @@
   }
 
   return false;
 }
 
 bool BrokerAddTargetPeer(HANDLE peer_process) {
   return g_broker_services->AddTargetPeer(peer_process) == sandbox::SBOX_ALL_OK;
 }
 
 }  // namespace content