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..420af085b49e22e4ce52dba80ff340694989117b 100644
--- a/chrome/renderer/printing/print_web_view_helper.cc
+++ b/chrome/renderer/printing/print_web_view_helper.cc
@@ -820,7 +820,8 @@ void PrintWebViewHelper::DidStartLoading() {
 
 void PrintWebViewHelper::DidStopLoading() {
   is_loading_ = false;
-  ShowScriptedPrintPreview();
+  if (!on_stop_loading_closure_.is_null())
+    on_stop_loading_closure_.Run();
 }
 
 // Prints |frame| which called window.print().
@@ -1711,6 +1712,9 @@ void PrintWebViewHelper::RequestPrintPreview(PrintPreviewRequestType type) {
         // 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.
+        on_stop_loading_closure_ =
+            base::Bind(&PrintWebViewHelper::ShowScriptedPrintPreview,
+                       base::Unretained(this));
       } else {
         base::MessageLoop::current()->PostTask(
             FROM_HERE,
@@ -1725,6 +1729,17 @@ 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())) {
+        on_stop_loading_closure_ =
+            base::Bind(&PrintWebViewHelper::RequestPrintPreview,
+                       base::Unretained(this),
+                       type);
+        return;
+      }
+
       break;
     }
     case PRINT_PREVIEW_USER_INITIATED_SELECTION: {
@@ -1733,6 +1748,15 @@ void PrintWebViewHelper::RequestPrintPreview(PrintPreviewRequestType type) {
       break;
     }
     case PRINT_PREVIEW_USER_INITIATED_CONTEXT_NODE: {
+      // Same situation as in PRINT_PREVIEW_USER_INITIATED_ENTIRE_FRAME.
+      if (is_loading_ && GetPlugin(print_preview_context_.source_frame())) {
+        on_stop_loading_closure_ =
+            base::Bind(&PrintWebViewHelper::RequestPrintPreview,
+                       base::Unretained(this),
+                       type);
+        return;
+      }
+
       params.webnode_only = true;
       break;
     }