Initial addition of Blimp engine crash client code (take 2)

chrome/common/crash_keys.cc

Index: chrome/common/crash_keys.cc
diff --git a/chrome/common/crash_keys.cc b/chrome/common/crash_keys.cc
index ef74b63f9dcf8a9f1137a85b7f6e3fd5a495b8fe..7f26bba626cd10d0dd8bdc8f938dfcc26d41119c 100644
--- a/chrome/common/crash_keys.cc
+++ b/chrome/common/crash_keys.cc
@@ -88,6 +88,9 @@ const char kZeroEncodeDetails[] = "zero-encode-details";
 size_t RegisterChromeCrashKeys() {
   // The following keys may be chunked by the underlying crash logging system,
   // but ultimately constitute a single key-value pair.
+  //
+  // If you're adding keys here, please also add them to the list in
+  // //blimp/engine/app/blimp_engine_crash_keys.cc
   base::debug::CrashKey fixed_keys[] = {
 #if defined(OS_MACOSX) || defined(OS_WIN)
     { kMetricsClientId, kSmallSize },