[win] Enable ModuleDatabase behind a flag.

chrome/browser/conflicts/module_database_win.cc

Index: chrome/browser/conflicts/module_database_win.cc
diff --git a/chrome/browser/conflicts/module_database_win.cc b/chrome/browser/conflicts/module_database_win.cc
index a336affbdf5b3bff2094a9adb65ac2a7235803e8..1c69dc657bf945694bb3b4a62019f70ca8f3c74e 100644
--- a/chrome/browser/conflicts/module_database_win.cc
+++ b/chrome/browser/conflicts/module_database_win.cc
@@ -19,6 +19,8 @@ static_assert(content::PROCESS_TYPE_BROWSER == 2,
               "assumes browser process type has value 2");
 constexpr uint32_t kMinProcessType = content::PROCESS_TYPE_BROWSER;
 
+ModuleDatabase* g_instance = nullptr;
+
 }  // namespace
 
 ModuleDatabase::ModuleDatabase(
@@ -27,6 +29,18 @@ ModuleDatabase::ModuleDatabase(
 
 ModuleDatabase::~ModuleDatabase() = default;
 
+// static
+ModuleDatabase* ModuleDatabase::GetInstance() {
+  return g_instance;
+}
+
+// static
+void ModuleDatabase::SetInstance(
+    std::unique_ptr<ModuleDatabase> module_database) {
+  // This is deliberately leaked.

[grt (UTC plus 2), 2017/01/06 09:44:58]

  DCHECK_EQ(nullptr, g_instance);

[chrisha, 2017/01/10 21:01:46]

Done.

+  g_instance = module_database.release();

[grt (UTC plus 2), 2017/01/06 09:44:58]

wdyt of adding a dtor with something like DCHECK_NE(g_instance, this);? or have
the dtor clear g_instance if it equals |this|?

[chrisha, 2017/01/10 21:01:46]

Sure, I'm fine with that.

+}
+
 void ModuleDatabase::OnProcessStarted(uint32_t process_id,
                                       uint64_t creation_time,
                                       content::ProcessType process_type) {