pepper: don't warn if PDF plugin is unavailable

chrome/common/pepper_plugin_registry.cc

Index: chrome/common/pepper_plugin_registry.cc
diff --git a/chrome/common/pepper_plugin_registry.cc b/chrome/common/pepper_plugin_registry.cc
index 7caf9c9403bcc9cc3e41b20258230d545872f060..ca4bf4299d601f9ba03725cd60e2e85029708602 100644
--- a/chrome/common/pepper_plugin_registry.cc
+++ b/chrome/common/pepper_plugin_registry.cc
@@ -101,11 +101,18 @@ void PepperPluginRegistry::GetPluginInfoFromSwitch(
 // static
 void PepperPluginRegistry::GetExtraPlugins(
     std::vector<PepperPluginInfo>* plugins) {
+  // Once we're sandboxed, we can't know if the PDF plugin is
+  // available or not; but this function is always called once before
+  // we're sandboxed.  So the first time through test if the file is
+  // available and then skip the check on subsequent calls if not.
+  static bool skip_pdf_plugin = false;
   FilePath path;
-  // We can't check for path existance here, since we are in the sandbox.
-  // If plugin is missing, it will later fail to
-  // load the library and the missing plugin message will be displayed.
-  if (PathService::Get(chrome::FILE_PDF_PLUGIN, &path)) {
+  if (!skip_pdf_plugin && PathService::Get(chrome::FILE_PDF_PLUGIN, &path)) {
+    if (!file_util::PathExists(path)) {
+      skip_pdf_plugin = true;
+      return;
+    }
+
     PepperPluginInfo pdf;
     pdf.path = path;
     pdf.name = "Chrome PDF Viewer";