Adding support for sampling crashes in Chrome on Windows.

chrome/browser/metrics/chrome_metrics_services_manager_client.cc

Index: chrome/browser/metrics/chrome_metrics_services_manager_client.cc
diff --git a/chrome/browser/metrics/chrome_metrics_services_manager_client.cc b/chrome/browser/metrics/chrome_metrics_services_manager_client.cc
index c1224a28180afad63684aa45e5b12ca5efec652b..a34827be512953e0586527dd1fa6ca0488ec3021 100644
--- a/chrome/browser/metrics/chrome_metrics_services_manager_client.cc
+++ b/chrome/browser/metrics/chrome_metrics_services_manager_client.cc
@@ -25,8 +25,27 @@
 #include "components/variations/variations_associated_data.h"
 #include "content/public/browser/browser_thread.h"
 
+#if defined(OS_WIN)
+#include "base/win/registry.h"
+#include "chrome/common/chrome_constants.h"
+#include "chrome/install_static/install_util.h"
+#include "chrome/installer/util/browser_distribution.h"
+#include "components/crash/content/app/crashpad.h"
+#endif  // OS_WIN
+
 namespace {
 
+#if defined(OS_WIN)
+// Type for the function pointer to enable and disable crash reporting on
+// windows. Needed because the function is loaded from chrome_elf.
+typedef void (*SetCrashUploadConsentPointer)(bool);

[scottmg, 2016/08/18 19:49:10]

SetUploadConsentPointer

[jwd, 2016/08/18 21:07:34]

Done.

+
+// The name of the function used to set the uploads enabled state in
+// components/crash/content/app/crashpad.cc. This is used to call the function
+// exported by the chrome_elf dll.
+const char kCrashpadUpdateConsentFunctionName[] = "SetUploadConsentImpl";
+#endif  // OS_WIN
+
 // Name of the variations param that defines the sampling rate.
 const char kRateParamName[] = "sampling_rate_per_mille";
 
@@ -171,6 +190,31 @@ bool ChromeMetricsServicesManagerClient::OnlyDoMetricsRecording() {
          cmdline->HasSwitch(switches::kEnableBenchmarking);
 }
 
+#if defined(OS_WIN)
+void ChromeMetricsServicesManagerClient::UpdateRunningServices(
+    bool may_record,
+    bool may_upload) {
+  // First, set the registry value so that Crashpad will have the sampling state
+  // now and for subsequent runs.
+  install_static::SetCollectStatsInSample(IsClientInSample());
+
+  // Next, get Crashpad to pick up the sampling state for this session.
+
+  // The crash reporting is handled by chrome_elf.dll.
+  HMODULE elf_module = GetModuleHandle(chrome::kChromeElfDllName);
+  static SetCrashUploadConsentPointer set_crash_enabled =

[scottmg, 2016/08/18 19:49:10]

set_upload_consent instead of set_crash_enabled.

[jwd, 2016/08/18 21:07:34]

Done.

+      reinterpret_cast<SetCrashUploadConsentPointer>(
+          GetProcAddress(elf_module, kCrashpadUpdateConsentFunctionName));
+
+  if (set_crash_enabled) {
+    // Crashpad will use the kRegUsageStatsInSample registry value to apply
+    // sampling correctly, but may_record already reflects the sampling state.
+    // This isn't a problem though, since they will be consistent.
+    set_crash_enabled(may_record && may_upload);
+  }
+}
+#endif  // defined(OS_WIN)
+
 metrics::MetricsStateManager*
 ChromeMetricsServicesManagerClient::GetMetricsStateManager() {
   DCHECK(thread_checker_.CalledOnValidThread());