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

Index: chrome/renderer/printing/print_web_view_helper.cc
diff --git a/chrome/renderer/printing/print_web_view_helper.cc b/chrome/renderer/printing/print_web_view_helper.cc
index 777eb69fa183c52236578b34969c60e803511b5e..3a094ab0b6e79745dbb936afa31e32af48355fd0 100644
--- a/chrome/renderer/printing/print_web_view_helper.cc
+++ b/chrome/renderer/printing/print_web_view_helper.cc
@@ -820,7 +820,10 @@ void PrintWebViewHelper::DidStartLoading() {
 
 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().
@@ -1699,6 +1702,10 @@ void PrintWebViewHelper::RequestPrintPreview(PrintPreviewRequestType type) {
   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.
@@ -1725,6 +1732,17 @@ void PrintWebViewHelper::RequestPrintPreview(PrintPreviewRequestType type) {
       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: {