Ok, here is a different approach at this change.

chrome/renderer/user_script_slave.cc

 // 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.
 
 #include "chrome/renderer/user_script_slave.h"
 
 #include "app/resource_bundle.h"
+#include "base/command_line.h"
 #include "base/histogram.h"
 #include "base/logging.h"
 #include "base/perftimer.h"
 #include "base/pickle.h"
 #include "base/shared_memory.h"
 #include "base/string_util.h"
+#include "chrome/common/child_process_logging.h"
+#include "chrome/common/chrome_switches.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/extension_constants.h"
 #include "chrome/renderer/extension_groups.h"
 #include "googleurl/src/gurl.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebFrame.h"
 
 #include "grit/renderer_resources.h"
 
 using WebKit::WebFrame;
 using WebKit::WebString;
@@ skipping 80 matching lines @@
     }
     for (size_t j = 0; j < script->css_scripts().size(); ++j) {
       const char* body = NULL;
       int body_length = 0;
       CHECK(pickle.ReadData(&iter, &body, &body_length));
       script->css_scripts()[j].set_external_content(
           base::StringPiece(body, body_length));
     }
   }
 
+  // Update the crash reporter with all loaded extensions. In single process,
+  // this has already been done in the browser code.
+  if (!CommandLine::ForCurrentProcess()->HasSwitch(switches::kSingleProcess)) {
+    std::vector<std::string> extension_ids;
+    for (size_t i = 0; i < num_scripts; ++i) {
+      DCHECK(!scripts_[i]->extension_id().empty());
+
+      // We must check this because there can be multiple scripts from a single
+      // extension. n^2, but meh, it's a small list.
+      if (std::find(extension_ids.begin(), extension_ids.end(),
+                    scripts_[i]->extension_id()) == extension_ids.end()) {
+        extension_ids.push_back(scripts_[i]->extension_id());
+      }
+    }
+
+    child_process_logging::SetActiveExtensions(extension_ids);
+  }
+
   return true;
 }
 
 // static
 void UserScriptSlave::InsertInitExtensionCode(
     std::vector<WebScriptSource>* sources, const std::string& extension_id) {
   DCHECK(sources);
   sources->insert(sources->begin(),
                   WebScriptSource(WebString::fromUTF8(
                   StringPrintf(kInitExtension, extension_id.c_str()))));
@@ skipping 93 matching lines @@
     if (num_scripts)
       UMA_HISTOGRAM_TIMES("Extensions.InjectIdle_Time", timer.Elapsed());
   } else {
     NOTREACHED();
   }
 
   LOG(INFO) << "Injected " << num_scripts << " scripts and " << num_css <<
       "css files into " << frame->url().spec().data();
   return true;
 }