[Mac] Log stack trace for OnChannelError() in bug 97285.

The hypothesis in comment #67 is that OnChannelError() is being called
to invalidate a channel, and the invalid channel is later being vended
from the cache.  This will verify if OnChannelError() was previously
called on the channel, and also provide a backtrace to determine what
the context was.

BUG=97285
TEST=crash server


Review URL: https://chromiumcodereview.appspot.com/10544038

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@140921 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 35 insertions, 0 deletions

diff --git a/content/common/np_channel_base.cc b/content/common/np_channel_base.cc
index d9b2e42..c310ffd 100644
--- a/content/common/np_channel_base.cc
+++ b/content/common/np_channel_base.cc
@@ -16,6 +16,25 @@
 #include "ipc/ipc_channel_posix.h"
 #endif
 
+// TODO(shess): Debugging for http://crbug.com/97285
+//
+// The hypothesis at #67 is that OnChannelError() is being called, but
+// the channel is not being removed from the cache.  Add code to
+// record the stack trace in OnChannelError(), and push it to breakpad
+// when the error case happens.
+#if defined(OS_MACOSX)
+#include "base/debug/stack_trace.h"
+#include "base/mac/crash_logging.h"
+#include "base/sys_string_conversions.h"
+
+namespace {
+
+// Breakpad key for the OnChannelError() backtrace.
+const char* kErrorTraceKey = "channel_error_bt";
+
+}  // namespace
+#endif
+
 typedef base::hash_map<std::string, scoped_refptr<NPChannelBase> > ChannelMap;
 static base::LazyInstance<ChannelMap>::Leaky
      g_channels = LAZY_INSTANCE_INITIALIZER;
@@ -37,6 +56,18 @@ NPChannelBase* NPChannelBase::GetChannel(
     channel = iter->second;
 #if defined(OS_POSIX)
     // Investigation for crbug.com/97285.
+#if defined(OS_MACOSX)
+    // If error_trace_ is set, that implies !channel_valid().  Log the
+    // trace under a breakpad key for debugging.  If there is no
+    // error_trace_, that implies that the Init() below is failing
+    // somehow.
+    if (channel->error_trace_.get()) {
+      size_t count = 0;
+      const void* const* addresses = channel->error_trace_->Addresses(&count);
+      base::mac::SetCrashKeyFromAddresses(
+          base::SysUTF8ToNSString(kErrorTraceKey), addresses, count);
+    }
+#endif
     CHECK(channel->channel_valid() || channel_handle.socket.fd != -1);
 #endif
   }
@@ -256,6 +287,10 @@ bool NPChannelBase::OnControlMessageReceived(const IPC::Message& msg) {
 }
 
 void NPChannelBase::OnChannelError() {
+#if defined(OS_MACOSX)
+  error_trace_.reset(new base::debug::StackTrace());
+#endif
+
   channel_valid_ = false;
 }