Simplify libcrash_dumper interface and make window_manager gen crash dumps

src/platform/crash/crash_dumper.h

Index: src/platform/crash/crash_dumper.h
diff --git a/src/platform/crash/crash_dumper.h b/src/platform/crash/crash_dumper.h
index 4dafbeb00f462ac000e1f31f87d95061b6d80018..04e69e4664f061cfe9674987b5f38baeb0db868c 100644
--- a/src/platform/crash/crash_dumper.h
+++ b/src/platform/crash/crash_dumper.h
@@ -5,16 +5,6 @@
 #ifndef CRASH_CRASH_DUMPER_H_
 #define CRASH_CRASH_DUMPER_H_
 
-#include <string>
-
-#include "base/scoped_ptr.h"
-
-namespace google_breakpad {
-class ExceptionHandler;
-}
-
-class FilePath;
-
 // Class to manage crash handling and dumping.  When Enable is called, all
 // crashes will be caught and stored to the appropriate crash directory.
 // The directory will be:
@@ -22,9 +12,17 @@ class FilePath;
 //   /var/spool/crash - for all other processes
 // The class takes care of creating the directories (even recreating them
 // at crash time in case the cryptohome mounting changes from Enable time.
+//
+// For most use cases, there is no need to include or call any functions
+// explicitly in this header file.  Crash dumping is enabled just by linking
+// in libcrash_dumper.
 
 class CrashDumper {
  public:
+  CrashDumper() {
+    Enable();
+  }
+
   ~CrashDumper() {
     if (IsEnabled()) {
       Disable();