Switch chrome_elf exception handling from breakpad to crashpad.

chrome_elf/crashpad_helper.cc

+// Copyright 2016 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.
+
+#include "chrome_elf/crashpad_helper.h"
+#include "third_party/crashpad/crashpad/client/crashpad_client.h"
+
+int GenerateCrashDump(EXCEPTION_POINTERS* exception_pointers) {
+  crashpad::CrashpadClient::DumpWithoutCrash(

[scottmg, 2016/06/22 19:38:07]

This is going to generate two crash dumps now, right? e.g. in the __try/__except
around BlNtMapViewOfSectionImpl we'd dump once, and then dump again when we get
to the UnhandledExceptionFilter? (maybe this is more a question for Robert than
Ananta)

[robertshield, 2016/06/22 19:47:45]

Sometimes, yes. In practice quite often this is hit by e.g. foo.dll loading
bar.dll loading baz.dll with an exception somewhere down the chain that is
caught and handled by something (not us) further up like foo.dll or bar.dll.

In this case the exception doesn't hit the unhandled exception handler, which is
why we also catch it in BlNtMapViewOfSectionImpl . 

+    *(exception_pointers->ContextRecord));
+  return EXCEPTION_CONTINUE_SEARCH;
+}