Merge trunk r166585 to the 24.0.1312 branch.

chrome/browser/chrome_browser_main_mac.mm

Index: chrome/browser/chrome_browser_main_mac.mm
===================================================================
--- chrome/browser/chrome_browser_main_mac.mm	(revision 167190)
+++ chrome/browser/chrome_browser_main_mac.mm	(working copy)
@@ -5,6 +5,7 @@
 #include "chrome/browser/chrome_browser_main_mac.h"
 
 #import <Cocoa/Cocoa.h>
+#include <sys/sysctl.h>
 
 #include "base/command_line.h"
 #include "base/debug/debugger.h"
@@ -12,6 +13,7 @@
 #include "base/mac/bundle_locations.h"
 #include "base/mac/mac_util.h"
 #include "base/memory/scoped_nsobject.h"
+#include "base/metrics/histogram.h"
 #include "base/path_service.h"
 #include "chrome/app/breakpad_mac.h"
 #import "chrome/browser/app_controller_mac.h"
@@ -49,6 +51,103 @@
     @"KeychainReauthorizeAtUpdateMay2012";
 const int kKeychainReauthorizeAtUpdateMaxTries = 3;
 
+// This is one enum instead of two so that the values can be correlated in a
+// histogram.
+enum CatSixtyFour {
+  // Older than any expected cat.
+  SABER_TOOTHED_CAT_32 = 0,
+  SABER_TOOTHED_CAT_64,
+
+  // Known cats.
+  SNOW_LEOPARD_32,
+  SNOW_LEOPARD_64,
+  LION_32,  // Unexpected, Lion requires a 64-bit CPU.
+  LION_64,
+  MOUNTAIN_LION_32,  // Unexpected, Mountain Lion requires a 64-bit CPU.
+  MOUNTAIN_LION_64,
+
+  // DON'T add new constants here. It's important to keep the constant values,
+  // um, constant. Add new constants at the bottom.
+
+  // Newer than any known cat.
+  FUTURE_CAT_32,  // Unexpected, it's unlikely Apple will un-obsolete old CPUs.
+  FUTURE_CAT_64,
+
+  // What if the bitsiness of the CPU can't be determined?
+  SABER_TOOTHED_CAT_DUNNO,
+  SNOW_LEOPARD_DUNNO,
+  LION_DUNNO,
+  MOUNTAIN_LION_DUNNO,
+  FUTURE_CAT_DUNNO,
+
+  // Add new constants here.
+
+  CAT_SIXTY_FOUR_MAX
+};
+
+CatSixtyFour CatSixtyFourValue() {
+#if defined(ARCH_CPU_64_BITS)
+  // If 64-bit code is running, then it's established that this CPU can run
+  // 64-bit code, and no further inquiry is necessary.
+  int cpu64 = 1;
+  bool cpu64_known = true;
+#else
+  // Check a sysctl conveniently provided by the kernel that identifies
+  // whether the CPU supports 64-bit operation. Note that this tests the
+  // actual hardware capabilities, not the bitsiness of the running process,
+  // and not the bitsiness of the running kernel. The value thus determines
+  // whether the CPU is capable of running 64-bit programs (in the presence of
+  // proper OS runtime support) without regard to whether the current program
+  // is 64-bit (it may not be) or whether the current kernel is (the kernel
+  // can launch cross-bitted user-space tasks).
+
+  int cpu64;
+  size_t len = sizeof(cpu64);
+  const char kSysctlName[] = "hw.cpu64bit_capable";
+  bool cpu64_known = sysctlbyname(kSysctlName, &cpu64, &len, NULL, 0) == 0;
+  if (!cpu64_known) {
+    PLOG(WARNING) << "sysctlbyname(\"" << kSysctlName << "\")";
+  }
+#endif
+
+  if (base::mac::IsOSSnowLeopard()) {
+    return cpu64_known ? (cpu64 ? SNOW_LEOPARD_64 : SNOW_LEOPARD_32) :
+                         SNOW_LEOPARD_DUNNO;
+  }
+  if (base::mac::IsOSLion()) {
+    return cpu64_known ? (cpu64 ? LION_64 : LION_32) :
+                         LION_DUNNO;
+  }
+  if (base::mac::IsOSMountainLion()) {
+    return cpu64_known ? (cpu64 ? MOUNTAIN_LION_64 : MOUNTAIN_LION_32) :
+                         MOUNTAIN_LION_DUNNO;
+  }
+  if (base::mac::IsOSLaterThanMountainLion_DontCallThis()) {
+    return cpu64_known ? (cpu64 ? FUTURE_CAT_64 : FUTURE_CAT_32) :
+                         FUTURE_CAT_DUNNO;
+  }
+
+  // If it's not any of the expected OS versions or later than them, it must
+  // be prehistoric.
+  return cpu64_known ? (cpu64 ? SABER_TOOTHED_CAT_64 : SABER_TOOTHED_CAT_32) :
+                       SABER_TOOTHED_CAT_DUNNO;
+}
+
+void RecordCatSixtyFour() {
+  CatSixtyFour cat_sixty_four = CatSixtyFourValue();
+
+  // Set this higher than the highest value in the CatSixtyFour enum to
+  // provide some headroom and then leave it alone. See HISTOGRAM_ENUMERATION
+  // in base/metrics/histogram.h.
+  const int kMaxCatsAndSixtyFours = 32;
+  COMPILE_ASSERT(kMaxCatsAndSixtyFours >= CAT_SIXTY_FOUR_MAX,
+                 CatSixtyFour_enum_grew_too_large);
+
+  UMA_HISTOGRAM_ENUMERATION("OSX.CatSixtyFour",
+                            cat_sixty_four,
+                            kMaxCatsAndSixtyFours);
+}
+
 }  // namespace
 
 void RecordBreakpadStatusUMA(MetricsService* metrics) {
@@ -102,6 +201,8 @@
     CommandLine* singleton_command_line = CommandLine::ForCurrentProcess();
     singleton_command_line->AppendSwitch(switches::kNoStartupWindow);
   }
+
+  RecordCatSixtyFour();
 }
 
 void ChromeBrowserMainPartsMac::PreMainMessageLoopStart() {