SyzyASAN: Export experiment state to finch synthetic field trials.

chrome/browser/chrome_browser_main.cc

Index: chrome/browser/chrome_browser_main.cc
diff --git a/chrome/browser/chrome_browser_main.cc b/chrome/browser/chrome_browser_main.cc
index fe298463c97f143300c8abd98da235f4be79f648..5edc8ab92769006d3ea0d0876f30e9c2cab4694f 100644
--- a/chrome/browser/chrome_browser_main.cc
+++ b/chrome/browser/chrome_browser_main.cc
@@ -1224,33 +1224,70 @@ void ChromeBrowserMainParts::PostProfileInit() {
     chrome_extra_parts_[i]->PostProfileInit();
 }
 
-void ChromeBrowserMainParts::PreBrowserStart() {
-  TRACE_EVENT0("startup", "ChromeBrowserMainParts::PreBrowserStart");
-  for (size_t i = 0; i < chrome_extra_parts_.size(); ++i)
-    chrome_extra_parts_[i]->PreBrowserStart();
+#if defined(SYZYASAN)
 
-  three_d_observer_.reset(new ThreeDAPIObserver());
+// This function must be in the global namespace as it needs to be friended
+// by ChromeMEtricsServiceAccessor.

[Alexei Svitkine (slow), 2016/05/04 16:25:38]

Nit: ME -> Me

+void SyzyASANRegisterExperiment(const char* name, const char* group) {
+  ChromeMetricsServiceAccessor::RegisterSyntheticFieldTrial(name, group);
+}
+
+namespace {
+
+void WINAPI SyzyASANExperimentCallback(const char* name, const char* group) {
+  // Indirect through the function above, so that the friend declaration doesn't
+  // need the ugly calling convention.
+  SyzyASANRegisterExperiment(name, group);
+}
+
+void SetupSyzyASAN() {
+  typedef VOID(WINAPI* SyzyASANExperimentCallbackFn)(const char* name,
+                                                     const char* group);
+  typedef VOID(WINAPI* SyzyASANEnumFeaturesFn)(SyzyASANExperimentCallbackFn);
+  HMODULE syzyasan_handle = ::GetModuleHandle(L"syzyasan_rtl.dll");
+  if (!syzyasan_handle)
+    return;
+
+  // Export the SyzyASAN experiments as synthetic field trials.
+  SyzyASANEnumFeaturesFn syzyasan_enum_features =
+      reinterpret_cast<SyzyASANEnumFeaturesFn>(
+            ::GetProcAddress(syzyasan_handle, "asan_EnumFeatures"));
+  if (syzyasan_enum_features) {
+    syzyasan_enum_features(&SyzyASANExperimentCallback);
+  }
 
-#if defined(SYZYASAN)
   // Enable the deferred free mechanism in the syzyasan module, which helps the
   // performance by deferring some work on the critical path to a background
   // thread.
   if (base::FeatureList::IsEnabled(features::kSyzyasanDeferredFree)) {
     typedef VOID(WINAPI * SyzyasanEnableDeferredFreeThreadFunc)(VOID);
-    HMODULE syzyasan_handle = ::GetModuleHandle(L"syzyasan_rtl.dll");
     bool success = false;
-    if (syzyasan_handle) {
-      SyzyasanEnableDeferredFreeThreadFunc syzyasan_enable_deferred_free =
-          reinterpret_cast<SyzyasanEnableDeferredFreeThreadFunc>(
-              ::GetProcAddress(syzyasan_handle,
-                               "asan_EnableDeferredFreeThread"));
-      if (syzyasan_enable_deferred_free) {
-        syzyasan_enable_deferred_free();
-        success = true;
-      }
+    SyzyasanEnableDeferredFreeThreadFunc syzyasan_enable_deferred_free =
+        reinterpret_cast<SyzyasanEnableDeferredFreeThreadFunc>(
+            ::GetProcAddress(syzyasan_handle,
+                             "asan_EnableDeferredFreeThread"));
+    if (syzyasan_enable_deferred_free) {
+      syzyasan_enable_deferred_free();
+      success = true;
     }
     UMA_HISTOGRAM_BOOLEAN("Syzyasan.DeferredFreeWasEnabled", success);
   }
+}
+
+}  // namespace
+
+#endif  // SYZYASAN
+
+
+void ChromeBrowserMainParts::PreBrowserStart() {
+  TRACE_EVENT0("startup", "ChromeBrowserMainParts::PreBrowserStart");
+  for (size_t i = 0; i < chrome_extra_parts_.size(); ++i)
+    chrome_extra_parts_[i]->PreBrowserStart();
+
+  three_d_observer_.reset(new ThreeDAPIObserver());
+
+#if defined(SYZYASAN)
+  SetupSyzyASAN();
 #endif
 
 // Start the tab manager here so that we give the most amount of time for the