Fix various issues from r343263.

chrome/browser/printing/print_preview_dialog_controller.cc

Index: chrome/browser/printing/print_preview_dialog_controller.cc
diff --git a/chrome/browser/printing/print_preview_dialog_controller.cc b/chrome/browser/printing/print_preview_dialog_controller.cc
index 3ec3df13e803bf8fa2fb4025faf98b15b7371cff..1303dc8ba7574346a2951f2083d33d22b4274035 100644
--- a/chrome/browser/printing/print_preview_dialog_controller.cc
+++ b/chrome/browser/printing/print_preview_dialog_controller.cc
@@ -183,9 +183,9 @@ WebContents* PrintPreviewDialogController::GetOrCreatePreviewDialog(
 
 WebContents* PrintPreviewDialogController::GetPrintPreviewForContents(
     WebContents* contents) const {
-  // If this WebContents relies on another for its preview dialog, we
-  // need to act as if we are looking for the proxied content's dialog.
-  PrintPreviewDialogMap::const_iterator proxied =
+  // If this WebContents relies on another for its preview dialog, look for the
+  // original initiator.
+  DistilledContentsMap::const_iterator proxied =
       proxied_dialog_map_.find(contents);
   if (proxied != proxied_dialog_map_.end()) {
     contents = proxied->second;
@@ -387,14 +387,16 @@ WebContents* PrintPreviewDialogController::CreatePrintPreviewDialog(
 }
 
 void PrintPreviewDialogController::AddProxyDialogForWebContents(
-    WebContents* source,
-    WebContents* target) {
-  proxied_dialog_map_[source] = target;
+    WebContents* distilled_contents,
+    WebContents* initiator) {
+  DCHECK(!ContainsKey(proxied_dialog_map_, distilled_contents));
+  proxied_dialog_map_[distilled_contents] = initiator;
 }
 
 void PrintPreviewDialogController::RemoveProxyDialogForWebContents(
-    WebContents* source) {
-  proxied_dialog_map_.erase(source);
+    WebContents* distilled_contents) {
+  size_t erased = proxied_dialog_map_.erase(distilled_contents);
+  DCHECK_EQ(1U, erased);
 }
 
 void PrintPreviewDialogController::SaveInitiatorTitle(