Add support for Sawbuck to Content Shell (ETW tracing).

Until Sawbuck gets updated (I plan to do that soon), devs have to
add a few registry entries for this to work, but that's simple to
do and a one time thing per machine and the instructions are in the code.

TEST=Content Shell and Sawbuck should work together (see above).


Review URL: https://chromiumcodereview.appspot.com/10825080

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@149294 0039d316-1c4b-4281-b951-d872f2087c98

content/shell/shell_main_delegate.cc

@@ -27,8 +27,30 @@
 #include "content/shell/paths_mac.h"
 #endif  // OS_MACOSX
 
+#if defined(OS_WIN)
+#include "base/logging_win.h"
+#include <initguid.h>
+#endif
+
 namespace {
 
+#if defined(OS_WIN)
+// If "Content Shell" doesn't show up in your list of trace providers in
+// Sawbuck, add these registry entries to your machine (NOTE the optional
+// Wow6432Node key for x64 machines):
+// 1. Find:  HKLM\SOFTWARE\[Wow6432Node\]Google\Sawbuck\Providers
+// 2. Add a subkey with the name "{6A3E50A4-7E15-4099-8413-EC94D8C2A4B6}"
+// 3. Add these values:
+//    "default_flags"=dword:00000001
+//    "default_level"=dword:00000004
+//    @="Content Shell"
+
+// {6A3E50A4-7E15-4099-8413-EC94D8C2A4B6}
+const GUID kContentShellProviderName = {
+    0x6a3e50a4, 0x7e15, 0x4099,
+        { 0x84, 0x13, 0xec, 0x94, 0xd8, 0xc2, 0xa4, 0xb6 } };
+#endif
+
 void InitLogging() {
   FilePath log_filename;
   PathService::Get(base::DIR_EXE, &log_filename);
@@ -56,6 +78,11 @@ ShellMainDelegate::~ShellMainDelegate() {
 }
 
 bool ShellMainDelegate::BasicStartupComplete(int* exit_code) {
+#if defined(OS_WIN)
+  // Enable trace control and transport through event tracing for Windows.
+  logging::LogEventProvider::Initialize(kContentShellProviderName);
+#endif
+
   if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kDumpRenderTree)) {
     InitLogging();
     CommandLine::ForCurrentProcess()->AppendSwitch(