Webview tag creation should be using storage partitions.

content/browser/browser_plugin/browser_plugin_embedder.cc

Index: content/browser/browser_plugin/browser_plugin_embedder.cc
diff --git a/content/browser/browser_plugin/browser_plugin_embedder.cc b/content/browser/browser_plugin/browser_plugin_embedder.cc
index abdde143de2e21e2cbeac70838a506ff710fb414..7e283fe4e2ec92c3a93bda09912d34cb80c8e98f 100644
--- a/content/browser/browser_plugin/browser_plugin_embedder.cc
+++ b/content/browser/browser_plugin/browser_plugin_embedder.cc
@@ -21,6 +21,7 @@
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/web_contents_view.h"
 #include "content/public/common/url_constants.h"
+#include "net/base/escape.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebInputEvent.h"
 #include "ui/gfx/size.h"
 #include "ui/surface/transport_dib.h"
@@ -88,11 +89,30 @@ void BrowserPluginEmbedder::CreateGuest(RenderViewHost* render_view_host,
   BrowserPluginGuest* guest = GetGuestByInstanceID(instance_id);
   CHECK(!guest);
 
+  // Validate that the partition id coming from the renderer is valid UTF-8,
+  // since we depend on this in other parts of the code, such as FilePath
+  // creation.
+  CHECK(IsStringUTF8(storage_partition_id));

[Charlie Reis, 2012/11/06 00:17:18]

Sanity check: Is crashing the browser process the right response to this?  Or
should we be trying something like clearing it out and killing the renderer,
since the renderer is the one to blame?

[nasko, 2012/11/07 00:33:57]

Done.

+
   const std::string& host =
       render_view_host->GetSiteInstance()->GetSiteURL().host();
+  std::string url_encoded_partition =
+      net::EscapeQueryParamValue(storage_partition_id, false);
+
+  // The SiteInstance of a given webview tag is based on the fact that it's a
+  // guest process in addition to which platform application the tag belongs to
+  // and what storage partition is in use, rather than the URL that the tag is
+  // being navigated to.
+  GURL guest_site(
+      base::StringPrintf("%s://%s/%s?%s", chrome::kGuestScheme,
+                         host.c_str(), persist_storage ? "persist" : "",
+                         url_encoded_partition.c_str()));
+  SiteInstance* guest_site_instance = SiteInstance::CreateForURL(

[Charlie Reis, 2012/11/06 00:17:18]

Not important for this CL, but if I understand correctly, this move from
WebContents to BPE is nice because it will let the BPE keep a single
BrowsingInstance for all its guest SiteInstances.  That will group them together
in the same process.

[nasko, 2012/11/06 01:21:52]

Yes. It is not done yet, I will do it in a follow up CL.

+      web_contents()->GetBrowserContext(), guest_site);
+
   guest_web_contents = WebContentsImpl::CreateGuest(
       web_contents()->GetBrowserContext(),
-      host,
+      guest_site_instance,
       instance_id,
       focused,
       visible);