Make startup_tests build and work on Mac.

chrome/common/chrome_constants.cc

Index: chrome/common/chrome_constants.cc
diff --git a/chrome/common/chrome_constants.cc b/chrome/common/chrome_constants.cc
index 9c248cd7d4fc08f5c4604c02265f06df21ddd000..e0d53bee7f5925af8904d0acb292116a34c6353b 100644
--- a/chrome/common/chrome_constants.cc
+++ b/chrome/common/chrome_constants.cc
@@ -16,7 +16,16 @@ namespace chrome {
 const wchar_t kBrowserProcessExecutableName[] = L"chrome.exe";
 #elif defined(OS_LINUX)
 const wchar_t kBrowserProcessExecutableName[] = L"chrome";
+#elif defined(OS_MACOSX)
+const wchar_t kBrowserProcessExecutableName[] =
+// TODO(thomasvl): Un-hardcode path inside the bundle in case we want to use
+// this constant for something other than test code.
+#if defined(GOOGLE_CHROME_BUILD)
+    L"Chrome.app/Contents/MacOS/Chrome";
+#else
+    L"Chromium.app/Contents/MacOS/Chromium";
 #endif
+#endif  // defined(MACOSX)
 #if defined(GOOGLE_CHROME_BUILD)
 const wchar_t kBrowserAppName[] = L"Chrome";
 const char    kStatsFilename[] = "ChromeStats2";