Revert of Crashpad Windows: Use the Crashpad client instead of Breakpad on Windows

components/crash/core/common/crash_keys.h

Index: components/crash/core/common/crash_keys.h
diff --git a/components/crash/core/common/crash_keys.h b/components/crash/core/common/crash_keys.h
index 6ddb35625ca16fb7475519424e28df81a5daf3f4..70b77ae1165a3ddb3209300e7fc6cf52d8b56dc9 100644
--- a/components/crash/core/common/crash_keys.h
+++ b/components/crash/core/common/crash_keys.h
@@ -48,13 +48,10 @@
 
 // The GUID used to identify this client to the crash system.
 #if defined(OS_MACOSX)
-// When using Crashpad, the crash reporting client ID is the responsibility of
-// Crashpad. It is not set directly by Chrome. To make the metrics client ID
-// available on the server, it's stored in a distinct key.
+// On Mac OS X, the crash reporting client ID is the responsibility of Crashpad.
+// It is not set directly by Chrome. To make the metrics client ID available on
+// the server, it's stored in a distinct key.
 extern const char kMetricsClientId[];
-#elif defined(OS_WIN)
-extern const char kMetricsClientId[];
-extern const char kClientId[];
 #else
 // When using Breakpad instead of Crashpad, the crash reporting client ID is the
 // same as the metrics client ID.