[DevTools] Fix DCHECK in DevToolsUIBindings

chrome/browser/devtools/devtools_ui_bindings.cc

 // Copyright 2014 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/browser/devtools/devtools_ui_bindings.h"
 
 #include "base/command_line.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "base/metrics/histogram.h"
@@ skipping 395 matching lines @@
 
 DevToolsUIBindings::DevToolsUIBindings(content::WebContents* web_contents)
     : profile_(Profile::FromBrowserContext(web_contents->GetBrowserContext())),
       android_bridge_(DevToolsAndroidBridge::Factory::GetForProfile(profile_)),
       web_contents_(web_contents),
       delegate_(new DefaultBindingsDelegate(web_contents_)),
       device_count_updates_enabled_(false),
       devices_updates_enabled_(false),
       frontend_loaded_(false),
       weak_factory_(this) {
-  DCHECK(android_bridge_);
   g_instances.Get().push_back(this);
   frontend_contents_observer_.reset(new FrontendWebContentsObserver(this));
   web_contents_->GetMutableRendererPrefs()->can_accept_load_drops = false;
 
   file_helper_.reset(new DevToolsFileHelper(web_contents_, profile_));
   file_system_indexer_ = new DevToolsFileSystemIndexer();
   extensions::ChromeExtensionWebContentsObserver::CreateForWebContents(
       web_contents_);
 
   // Wipe out page icon so that the default application icon is used.
@@ skipping 350 matching lines @@
 void DevToolsUIBindings::RecordActionUMA(const std::string& name, int action) {
   if (name == kDevToolsActionTakenHistogram)
     UMA_HISTOGRAM_ENUMERATION(name, action, kDevToolsActionTakenBoundary);
   else if (name == kDevToolsPanelShownHistogram)
     UMA_HISTOGRAM_ENUMERATION(name, action, kDevToolsPanelShownBoundary);
 }
 
 void DevToolsUIBindings::SendJsonRequest(const DispatchCallback& callback,
                                          const std::string& browser_id,
                                          const std::string& url) {
+  if (!android_bridge_) {
+    callback.Run(nullptr);
+    return;
+  }
   android_bridge_->SendJsonRequest(browser_id, url,
       base::Bind(&DevToolsUIBindings::JsonReceived,
                  weak_factory_.GetWeakPtr(),
                  callback));
 }
 
 void DevToolsUIBindings::JsonReceived(const DispatchCallback& callback,
                                       int result,
                                       const std::string& message) {
   if (result != net::OK) {
@@ skipping 241 matching lines @@
   if (frontend_loaded_)
     return;
   frontend_loaded_ = true;
 
   // Call delegate first - it seeds importants bit of information.
   delegate_->OnLoadCompleted();
 
   UpdateTheme();
   AddDevToolsExtensionsToClient();
 }