win: Implement CRASHPAD_SIMULATE_CRASH()

snapshot/win/exception_snapshot_win.cc

Index: snapshot/win/exception_snapshot_win.cc
diff --git a/snapshot/win/exception_snapshot_win.cc b/snapshot/win/exception_snapshot_win.cc
index 731669ad49cd41c58a5d26ae2abdb1cfb6c9b252..d7fb4c3cc2e881398e58570e679d875092a002de 100644
--- a/snapshot/win/exception_snapshot_win.cc
+++ b/snapshot/win/exception_snapshot_win.cc
@@ -134,11 +134,20 @@ bool ExceptionSnapshotWin::InitializeFromExceptionPointers(
     LOG(ERROR) << "EXCEPTION_POINTERS read failed";
     return false;
   }
-  if (!exception_pointers.ExceptionRecord) {
-    LOG(ERROR) << "null ExceptionRecord";
+
+  if (!process_reader.ReadMemory(
+          static_cast<WinVMAddress>(exception_pointers.ContextRecord),
+          sizeof(*context_record),
+          context_record)) {
+    LOG(ERROR) << "ContextRecord";
     return false;
   }
 
+  if (!exception_pointers.ExceptionRecord) {
+    LOG(INFO) << "null ExceptionRecord, not capturing any exception";

[Mark Mentovai, 2015/09/23 20:00:52]

This is fully expected now, I don’t think we need to log anything when this
happens. But this should have a comment saying that it happens for simulated
crashes.

[scottmg, 2015/09/24 19:16:52]

Done.

+    return true;
+  }
+
   ExceptionRecordType first_record;
   if (!process_reader.ReadMemory(
           static_cast<WinVMAddress>(exception_pointers.ExceptionRecord),
@@ -157,14 +166,6 @@ bool ExceptionSnapshotWin::InitializeFromExceptionPointers(
     LOG(WARNING) << "dropping chained ExceptionRecord";
   }
 
-  if (!process_reader.ReadMemory(
-          static_cast<WinVMAddress>(exception_pointers.ContextRecord),
-          sizeof(*context_record),
-          context_record)) {
-    LOG(ERROR) << "ContextRecord";
-    return false;
-  }
-
   return true;
 }