Ensure streams aren't intercepted unless their associated plugin is e…

…nabled

Previously streams would be intercepted even if the MimeHandlerView plugin
associated with them was disabled which would prevent the resource
from being download if a plugin wasn't being enabled to handle it.

BUG=459383

Review URL: https://codereview.chromium.org/933093002

Cr-Commit-Position: refs/heads/master@{#317673}

chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc

@@ -16,6 +16,7 @@
 #include "chrome/browser/download/download_request_limiter.h"
 #include "chrome/browser/download/download_resource_throttle.h"
 #include "chrome/browser/net/resource_prefetch_predictor_observer.h"
+#include "chrome/browser/plugins/plugin_prefs.h"
 #include "chrome/browser/prefetch/prefetch.h"
 #include "chrome/browser/prerender/prerender_manager.h"
 #include "chrome/browser/prerender/prerender_manager_factory.h"
@@ -37,6 +38,8 @@
 #include "components/variations/net/variations_http_header_provider.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_service.h"
+#include "content/public/browser/plugin_service.h"
+#include "content/public/browser/plugin_service_filter.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/resource_context.h"
@@ -207,6 +210,36 @@ void SendExecuteMimeTypeHandlerEvent(scoped_ptr<content::StreamInfo> stream,
       extension_id, web_contents, stream.Pass(), view_id, expected_content_size,
       embedded, render_process_id, render_frame_id);
 }
+
+// TODO(raymes): This won't return the right result if plugins haven't been
+// loaded yet. Fixing this properly really requires fixing crbug.com/443466.
+bool IsPluginEnabledForExtension(const Extension* extension,
+                                 const ResourceRequestInfo* info,
+                                 const std::string& mime_type,
+                                 const GURL& url) {
+  content::PluginService* service = content::PluginService::GetInstance();
+  std::vector<content::WebPluginInfo> plugins;
+  service->GetPluginInfoArray(url, mime_type, true, &plugins, nullptr);
+  content::PluginServiceFilter* filter = service->GetFilter();
+
+  for (auto& plugin : plugins) {
+    // Check that the plugin is running the extension.
+    if (plugin.path !=
+        base::FilePath::FromUTF8Unsafe(extension->url().spec())) {
+      continue;
+    }
+    // Check that the plugin is actually enabled.
+    if (!filter || filter->IsPluginAvailable(info->GetChildID(),
+                                             info->GetRenderFrameID(),
+                                             info->GetContext(),
+                                             url,
+                                             GURL(),
+                                             &plugin)) {
+      return true;
+    }
+  }
+  return false;
+}
 #endif  // !defined(ENABLE_EXTENSIONS)
 
 #if !defined(OS_ANDROID)
@@ -627,6 +660,13 @@ bool ChromeResourceDispatcherHostDelegate::ShouldInterceptResourceAsStream(
       *origin = Extension::GetBaseURLFromExtensionId(extension_id);
       target_info.extension_id = extension_id;
       if (!handler->handler_url().empty()) {
+        // This is reached in the case of MimeHandlerViews. If the
+        // MimeHandlerView plugin is disabled, then we shouldn't intercept the
+        // stream.
+        if (!IsPluginEnabledForExtension(extension, info, mime_type,
+                                         request->url())) {
+          continue;
+        }
         target_info.view_id = base::GenerateGUID();
         *payload = target_info.view_id;
       }