Fix for race condition where print preview hangs when attempting to print a PDF that hasn't loaded.

chrome/renderer/printing/print_web_view_helper.cc

 // Copyright (c) 2012 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/renderer/printing/print_web_view_helper.h"
 
 #include <string>
 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
@@ skipping 802 matching lines @@
     return !IsScriptInitiatedPrintTooFrequent(frame);
   return true;
 }
 
 void PrintWebViewHelper::DidStartLoading() {
   is_loading_ = true;
 }
 
 void PrintWebViewHelper::DidStopLoading() {
   is_loading_ = false;
-  ShowScriptedPrintPreview();
+  if (!on_stop_loading_closure_.is_null())
+    on_stop_loading_closure_.Run();
+  else
+    NOTREACHED();

[Vitaly Buka (NO REVIEWS), 2014/08/06 08:53:57]

NOTREACHED is incorrect here. DidStopLoading is going to be called even without
print preview.

[ivandavid, 2014/08/06 19:00:17]

Done.

 }
 
 // Prints |frame| which called window.print().
 void PrintWebViewHelper::PrintPage(blink::WebLocalFrame* frame,
                                    bool user_initiated) {
   DCHECK(frame);
 
   // Allow Prerendering to cancel this print request if necessary.
   if (prerender::PrerenderHelper::IsPrerendering(
           render_view()->GetMainRenderFrame())) {
@@ skipping 858 matching lines @@
             print_preview_context_.IsModifiable()));
   }
 }
 
 void PrintWebViewHelper::RequestPrintPreview(PrintPreviewRequestType type) {
   const bool is_modifiable = print_preview_context_.IsModifiable();
   const bool has_selection = print_preview_context_.HasSelection();
   PrintHostMsg_RequestPrintPreview_Params params;
   params.is_modifiable = is_modifiable;
   params.has_selection = has_selection;
+  on_stop_loading_closure_ =

[Vitaly Buka (NO REVIEWS), 2014/08/06 08:53:57]

this piece should be on line 1718

[ivandavid, 2014/08/06 19:00:17]

Ok. I put it after the comment.

[ivandavid, 2014/08/06 19:00:17]

Done.

+      base::Bind(&PrintWebViewHelper::ShowScriptedPrintPreview,
+                 base::Unretained(this));
+
   switch (type) {
     case PRINT_PREVIEW_SCRIPTED: {
       // Shows scripted print preview in two stages.
       // 1. PrintHostMsg_SetupScriptedPrintPreview blocks this call and JS by
       //    pumping messages here.
       // 2. PrintHostMsg_ShowScriptedPrintPreview shows preview once the
       //    document has been loaded.
       is_scripted_preview_delayed_ = true;
       if (is_loading_ && GetPlugin(print_preview_context_.source_frame())) {
         // Wait for DidStopLoading. Plugins may not know the correct
         // |is_modifiable| value until they are fully loaded, which occurs when
         // DidStopLoading() is called. Defer showing the preview until then.
       } else {
         base::MessageLoop::current()->PostTask(
             FROM_HERE,
             base::Bind(&PrintWebViewHelper::ShowScriptedPrintPreview,
                        weak_ptr_factory_.GetWeakPtr()));
       }
       IPC::SyncMessage* msg =
           new PrintHostMsg_SetupScriptedPrintPreview(routing_id());
       msg->EnableMessagePumping();
       Send(msg);
       is_scripted_preview_delayed_ = false;
       return;
     }
     case PRINT_PREVIEW_USER_INITIATED_ENTIRE_FRAME: {
+      // Wait for DidStopLoading. Continuing with this function while
+      // |is_loading_| is true will cause print preview to hang when try to
+      // print a PDF document.
+      if (is_loading_ && GetPlugin(print_preview_context_.source_frame())) {

[Vitaly Buka (NO REVIEWS), 2014/08/06 08:53:57]

Same is needed for PRINT_PREVIEW_USER_INITIATED_CONTEXT_NODE

[ivandavid, 2014/08/06 19:00:16]

Done.

[ivandavid, 2014/08/06 19:00:16]

Is it supposed to bind RequestPrintPreview() or ShowScriptPrintPreview()? I used
RequestPrintPreview(), but since I am not familiar with this piece of code, I
don't know if that's what should be used.

[Vitaly Buka (NO REVIEWS), 2014/08/06 21:00:36]

Yes, it should be RequestPrintPreview. Bind of RequestPrintPreview is just delay
of the current function until frame is loaded. We'd like to do the same even for
PRINT_PREVIEW_SCRIPTED, but it's exceptional case because we need to block
message handler and javascript.

PRINT_PREVIEW_USER_INITIATED_SELECTION should not be possible for plugin frames

On 2014/08/06 19:00:16, ivandavid wrote:

+        on_stop_loading_closure_ =
+            base::Bind(&PrintWebViewHelper::RequestPrintPreview,
+                       base::Unretained(this),
+                       type);
+        return;
+      }
+
       break;
     }
     case PRINT_PREVIEW_USER_INITIATED_SELECTION: {
       DCHECK(has_selection);
       params.selection_only = has_selection;
       break;
     }
     case PRINT_PREVIEW_USER_INITIATED_CONTEXT_NODE: {
       params.webnode_only = true;
       break;
@@ skipping 293 matching lines @@
 }
 
 void PrintWebViewHelper::PrintPreviewContext::ClearContext() {
   prep_frame_view_.reset();
   metafile_.reset();
   pages_to_render_.clear();
   error_ = PREVIEW_ERROR_NONE;
 }
 
 }  // namespace printing