Print Preview: Detecting plugin existence before generating the preview.

chrome/browser/ui/webui/print_preview_ui_html_source.cc

 // Copyright (c) 2011 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/ui/webui/print_preview_ui_html_source.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/message_loop.h"
@@ skipping 142 matching lines @@
     char* preview_data = reinterpret_cast<char*>(data_.first->memory());
     uint32 preview_data_size = data_.second;
 
     scoped_refptr<RefCountedBytes> html_bytes(new RefCountedBytes);
     html_bytes->data.resize(preview_data_size);
     std::vector<unsigned char>::iterator it = html_bytes->data.begin();
     for (uint32 i = 0; i < preview_data_size; ++i, ++it)
       *it = *(preview_data + i);
     SendResponse(request_id, html_bytes);
     return;
+  } else if (path == "dummy.pdf") {

[vandebo (ex-Chrome), 2011/05/12 02:10:12]

It occurs to me that since the plugin doesn't need a valid PDF, we don't even
need this code.  The error page would be returned instead.

[Lei Zhang, 2011/05/12 02:19:34]

I would double check and make sure that doesn't crash the PDF viewer.

[dpapad, 2011/05/12 17:26:44]

Removed the "else if". As far as detecting the existence of the plugin it works.
Do we care if the dummy-plugin crashes? It is removed from the DOM tree right
after checking if it is compatible.

[Lei Zhang, 2011/05/12 17:50:45]

Well, if it crashes, then it is taking down the renderer with it, so we do care.
But it sounds like you tested it and that's not happening.

+    scoped_refptr<RefCountedStaticMemory> dummy_bytes(
+        new RefCountedStaticMemory());
+    SendResponse(request_id, dummy_bytes);
+    return;
   } else {
     // Invalid request.
     scoped_refptr<RefCountedBytes> empty_bytes(new RefCountedBytes);
     SendResponse(request_id, empty_bytes);
     return;
   }
 }
 
 std::string PrintPreviewUIHTMLSource::GetMimeType(
     const std::string& path) const {
   // Print Preview Index page.
   if (path.empty())
     return "text/html";
   // Print Preview data.
   return "application/pdf";
 }