Allow empty strings to be written to the clipboard

content/browser/web_contents/web_drag_source_mac.mm

Index: content/browser/web_contents/web_drag_source_mac.mm
diff --git a/content/browser/web_contents/web_drag_source_mac.mm b/content/browser/web_contents/web_drag_source_mac.mm
index 875f892cad661029cdd8eb3059102f1cf8cf4649..f9e57a4ce54a22d49ef260163bca4a96aa19dc15 100644
--- a/content/browser/web_contents/web_drag_source_mac.mm
+++ b/content/browser/web_contents/web_drag_source_mac.mm
@@ -151,9 +151,9 @@ void PromiseWriterHelper(const WebDropData& drop_data,
 
   // HTML.
   if ([type isEqualToString:NSHTMLPboardType]) {
-    DCHECK(!dropData_->text_html.empty());
+    DCHECK(!dropData_->html.string().empty());
     // See comment on |kHtmlHeader| above.
-    [pboard setString:SysUTF16ToNSString(kHtmlHeader + dropData_->text_html)
+    [pboard setString:SysUTF16ToNSString(kHtmlHeader + dropData_->html.string())
               forType:NSHTMLPboardType];
 
   // URL.
@@ -206,8 +206,8 @@ void PromiseWriterHelper(const WebDropData& drop_data,
 
   // Plain text.
   } else if ([type isEqualToString:NSStringPboardType]) {
-    DCHECK(!dropData_->plain_text.empty());
-    [pboard setString:SysUTF16ToNSString(dropData_->plain_text)
+    DCHECK(!dropData_->text.string().empty());
+    [pboard setString:SysUTF16ToNSString(dropData_->text.string())
               forType:NSStringPboardType];
 
   // Custom MIME data.
@@ -375,7 +375,7 @@ void PromiseWriterHelper(const WebDropData& drop_data,
              owner:contentsView_];
 
   // HTML.
-  if (!dropData_->text_html.empty())
+  if (!dropData_->html.string().empty())
     [pasteboard_ addTypes:[NSArray arrayWithObject:NSHTMLPboardType]
                     owner:contentsView_];
 
@@ -439,7 +439,7 @@ void PromiseWriterHelper(const WebDropData& drop_data,
   }
 
   // Plain text.
-  if (!dropData_->plain_text.empty())
+  if (!dropData_->text.string().empty())
     [pasteboard_ addTypes:[NSArray arrayWithObject:NSStringPboardType]
                     owner:contentsView_];