Fix media galleries crash when the window is closed with config dialog open.

chrome/browser/extensions/api/media_galleries/media_galleries_api.cc

Index: chrome/browser/extensions/api/media_galleries/media_galleries_api.cc
diff --git a/chrome/browser/extensions/api/media_galleries/media_galleries_api.cc b/chrome/browser/extensions/api/media_galleries/media_galleries_api.cc
index 143096434049f2dd0f0a93cd83661e98d0f8056c..22f5e46994742a17f5ca236268c3c98c07d5860c 100644
--- a/chrome/browser/extensions/api/media_galleries/media_galleries_api.cc
+++ b/chrome/browser/extensions/api/media_galleries/media_galleries_api.cc
@@ -48,6 +48,7 @@ namespace {
 const char kDisallowedByPolicy[] =
     "Media Galleries API is disallowed by policy: ";
 const char kInvalidInteractive[] = "Unknown value for interactive.";
+const char kInvalidRPH[] = "The render process no longer exists.";
 
 // Checks whether the MediaGalleries API is currently accessible (it may be
 // disallowed even if an extension has the requisite permission).
@@ -121,7 +122,19 @@ void MediaGalleriesGetMediaFileSystemsFunction::GetAndReturnGalleries() {
 
 void MediaGalleriesGetMediaFileSystemsFunction::ReturnGalleries(
     const std::vector<MediaFileSystemInfo>& filesystems) {
-  const int child_id = render_view_host()->GetProcess()->GetID();
+  content::RenderViewHost* rvh = render_view_host();
+  if (!rvh) {
+    error_ = kInvalidRPH;

[asargent_no_longer_on_chrome, 2012/10/16 23:01:47]

If the RPH no longer exists, doesn't that mean it's not around to get the error
message in its callback anyway? If so then it's probably fine to omit setting
the error_ member (but we should still call SendResponse, to free up any
resources in the API dispatching system).

[vandebo (ex-Chrome), 2012/10/16 23:17:28]

Yea, I wasn't sure about that part.  Looking into it further,
UIThreadExtensionFunction::SendResponse doesn't call SendResponseImpl, which is
where error_ is consumed, so there's no need to set it.

Furthermore, that code assumes that if the rvh is valid, the rph will be valid
too, so I'm removing the rph check.

+    SendResponse(false);
+    return;
+  }
+  content::RenderProcessHost* rph = rvh->GetProcess();
+  if (!rph) {
+    error_ = kInvalidRPH;
+    SendResponse(false);
+    return;
+  }
+  const int child_id = rph->GetID();
   std::set<std::string> file_system_names;
   base::ListValue* list = new base::ListValue();
   for (size_t i = 0; i < filesystems.size(); i++) {