[Mac] Log some NSException info with crash dumps.

chrome/browser/chrome_application_mac.mm

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "chrome/browser/chrome_application_mac.h"
 
 #import "base/histogram.h"
 #import "base/logging.h"
 #import "base/scoped_nsobject.h"
 #import "chrome/app/breakpad_mac.h"
@@ skipping 178 matching lines @@
 // we attempt to track and report them.
 - (void)reportException:(NSException *)anException {
   // If we throw an exception in this code, we can create an infinite
   // loop.  If we throw out of the if() without resetting
   // |reportException|, we'll stop reporting exceptions for this run.
   static BOOL reportingException = NO;
   DCHECK(!reportingException);
   if (!reportingException) {
     reportingException = YES;
     CrApplicationNSException::RecordExceptionWithUma(anException);
+
+    // Store some human-readable information in breakpad keys in case
+    // there is a crash.  Since breakpad does not provide infinite
+    // storage, we track two exceptions.  The first exception thrown
+    // is tracked because it may be the one which caused the system to
+    // go off the rails.  The last exception thrown is tracked because
+    // it may be the one most directly associated with the crash.
+    static const NSString* kFirstExceptionKey = @"firstexception";
+    static BOOL trackedFirstException = NO;
+    static const NSString* kLastExceptionKey = @"lastexception";
+
+    // TODO(shess): It would be useful to post some stacktrace info
+    // from the exception.
+    // 10.6 has -[NSException callStackSymbols]
+    // 10.5 has -[NSException callStackReturnAddresses]
+    // 10.5 has backtrace_symbols().
+    // I've tried to combine the latter two, but got nothing useful.
+    // The addresses are right, though, maybe we could train the crash
+    // server to decode them for us.
+
+    NSString* value = [NSString stringWithFormat:@"%@ reason %@",
+                                [anException name], [anException reason]];
+    if (!trackedFirstException) {
+      SetCrashKeyValue(kFirstExceptionKey, value);
+      trackedFirstException = YES;
+    } else {
+      SetCrashKeyValue(kLastExceptionKey, value);
+    }
+
     reportingException = NO;
   }
 
   [super reportException:anException];
 }
 
 @end
 
 namespace CrApplicationCC {
 
 void Terminate() {
   [NSApp terminate:nil];
 }
 
 }  // namespace CrApplicationCC