Avoid a crash when starting a download by disallowing downloads

Chromium crashes when starting a download if a content::DownloadManagerDelegate
is not provided. We now provide a default implementation of
content::DownloadManagerDelegate which disallows all downloads.

brightray/brightray.gyp

@@ -36,6 +36,8 @@
         'browser/default_web_contents_delegate_mac.mm',
         'browser/devtools_delegate.cc',
         'browser/devtools_delegate.h',
+        'browser/download_manager_delegate.cc',
+        'browser/download_manager_delegate.h',
         'browser/inspectable_web_contents.cc',
         'browser/inspectable_web_contents.h',
         'browser/inspectable_web_contents_impl.cc',

brightray/browser/browser_context.cc

@@ -4,6 +4,7 @@
 
 #include "browser_context.h"
 
+#include "browser/download_manager_delegate.h"
 #include "browser/inspectable_web_contents_impl.h"
 #include "browser/network_delegate.h"
 #include "common/application_info.h"
@@ -116,7 +117,9 @@ content::ResourceContext* BrowserContext::GetResourceContext() {
 }
 
 content::DownloadManagerDelegate* BrowserContext::GetDownloadManagerDelegate() {
-  return nullptr;
+  if (!download_manager_delegate_)
+    download_manager_delegate_.reset(new DownloadManagerDelegate);
+  return download_manager_delegate_.get();
 }
 
 content::GeolocationPermissionContext* BrowserContext::GetGeolocationPermissionContext() {

brightray/browser/browser_context.h

@@ -13,6 +13,7 @@ class PrefService;
 
 namespace brightray {
 
+class DownloadManagerDelegate;
 class NetworkDelegate;
 class URLRequestContextGetter;
 
@@ -55,6 +56,7 @@ private:
   scoped_ptr<ResourceContext> resource_context_;
   scoped_refptr<URLRequestContextGetter> url_request_getter_;
   scoped_ptr<PrefService> prefs_;
+  scoped_ptr<DownloadManagerDelegate> download_manager_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserContext);
 };

brightray/browser/download_manager_delegate.cc

@@ -0,0 +1,11 @@
+#include "browser/download_manager_delegate.h"
+
+namespace brightray {
+
+DownloadManagerDelegate::DownloadManagerDelegate() {
+}
+
+DownloadManagerDelegate::~DownloadManagerDelegate() {
+}
+
+}

brightray/browser/download_manager_delegate.h

@@ -0,0 +1,19 @@
+#ifndef BRIGHTRAY_BROWSER_DOWNLOAD_MANAGER_DELEGATE_H_
+#define BRIGHTRAY_BROWSER_DOWNLOAD_MANAGER_DELEGATE_H_
+
+#include "content/public/browser/download_manager_delegate.h"
+
+namespace brightray {
+
+class DownloadManagerDelegate : public content::DownloadManagerDelegate {
+ public:
+  DownloadManagerDelegate();
+  ~DownloadManagerDelegate();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(DownloadManagerDelegate);
+};
+
+}
+
+#endif