Don't intercept Flash navigations when the current page is the Flash download page.

chrome/browser/plugins/flash_download_interception.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/browser/plugins/flash_download_interception.h"
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/string_util.h"
 #include "chrome/browser/content_settings/host_content_settings_map_factory.h"
@@ skipping 13 matching lines @@
 #include "url/origin.h"
 
 using content::BrowserThread;
 using content::NavigationHandle;
 using content::NavigationThrottle;
 
 namespace {
 
 const char kWwwPrefix[] = "www.";
 
-// URLs that will be intercepted with any www. prefix pruned.
+// The URL of the page where Flash can be downloaded.
+const char kFlashDownloadURL[] = "get.adobe.com/flash";
+
+// URLs that will be intercepted with any www. prefix pruned. These should all
+// redirect to |kFlashDownloadURL|.
 const char* kFlashDownloadURLs[] = {
-    "get.adobe.com/flash", "macromedia.com/go/getflashplayer",
+    kFlashDownloadURL, "macromedia.com/go/getflashplayer",
     "adobe.com/go/getflashplayer", "adobe.com/go/gntray_dl_getflashplayer"};
 
 void DoNothing(blink::mojom::PermissionStatus result) {}
 
 bool InterceptNavigation(
     const GURL& source_url,
     content::WebContents* source,
     const navigation_interception::NavigationParams& params) {
   FlashDownloadInterception::InterceptFlashDownloadNavigation(source,
                                                               source_url);
@@ skipping 35 matching lines @@
     HostContentSettingsMap* host_content_settings_map,
     const GURL& source_url,
     const GURL& target_url,
     bool has_user_gesture) {
   if (!PluginUtils::ShouldPreferHtmlOverPlugins(host_content_settings_map))
     return false;
 
   if (!has_user_gesture)
     return false;
 
+  // If the navigation source is already the Flash download page, don't
+  // intercept the download. The user may be trying to download Flash.
+  if (base::StartsWith(source_url.GetContent(), kFlashDownloadURL,
+                       base::CompareCase::INSENSITIVE_ASCII)) {
+    return false;
+  }
+
   std::string target_url_str = target_url.GetContent();
   // Ignore www. if it's at the start of the URL.
   if (base::StartsWith(target_url_str, kWwwPrefix,
                        base::CompareCase::INSENSITIVE_ASCII)) {
     target_url_str =
         target_url_str.substr(sizeof(kWwwPrefix) - 1, std::string::npos);
   }
 
   for (const char* flash_url : kFlashDownloadURLs) {
     if (base::StartsWith(target_url_str, flash_url,
@@ skipping 29 matching lines @@
   GURL source_url = handle->GetWebContents()->GetLastCommittedURL();
   if (!ShouldStopFlashDownloadAction(host_content_settings_map, source_url,
                                      handle->GetURL(),
                                      handle->HasUserGesture())) {
     return nullptr;
   }
 
   return base::MakeUnique<navigation_interception::InterceptNavigationThrottle>(
       handle, base::Bind(&InterceptNavigation, source_url), true);
 }