Better bad message reporting from IO thread

content/browser/bad_message.cc

Index: content/browser/bad_message.cc
diff --git a/content/browser/bad_message.cc b/content/browser/bad_message.cc
index 183b46e70e95e9cde7b6867b37b9a29ababecbaa..4ef20f86cd8e7b6dd4ac02d6089ef9c503273a17 100644
--- a/content/browser/bad_message.cc
+++ b/content/browser/bad_message.cc
@@ -6,6 +6,7 @@
 
 #include "base/bind.h"
 #include "base/debug/crash_logging.h"
+#include "base/debug/dump_without_crashing.h"
 #include "base/logging.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/strings/string_number_conversions.h"
@@ -29,18 +30,29 @@ void ReceivedBadMessageOnUIThread(int render_process_id,
                                   BadMessageReason reason) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   RenderProcessHost* host = RenderProcessHost::FromID(render_process_id);
-  if (host)
-    ReceivedBadMessage(host, reason);
+  if (!host)
+    return;
+
+  LogBadMessage(reason);
+
+  // A dump has already been generated by the caller. Don't generate another.
+  host->ShutdownForBadMessage(
+      RenderProcessHost::CrashReportMode::NO_CRASH_DUMP);
 }
 
 }  // namespace
 
 void ReceivedBadMessage(RenderProcessHost* host, BadMessageReason reason) {
   LogBadMessage(reason);
-  host->ShutdownForBadMessage();
+  host->ShutdownForBadMessage(
+      RenderProcessHost::CrashReportMode::GENERATE_CRASH_DUMP);
 }
 
 void ReceivedBadMessage(int render_process_id, BadMessageReason reason) {
+  // We generate a crash dump here since generating one after posting the UI
+  // thread is mostly useless.
+  base::debug::DumpWithoutCrashing();

[Charlie Reis, 2017/01/12 00:39:30]

I just looked at a crash report that hit this (9fa49da580000000), and it's
missing the "bad_message_reason" crash key that gets set in LogBadMessage.  Can
you take a look at how to restore that key for IO thread crashes?

The key helps disambiguate when there are multiple renderer kills in a given
method, and it puts the reason code in the magic signature itself.

+
   if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
     BrowserThread::PostTask(
         BrowserThread::UI,