Support partitioning of storage contexts based on render_id.

content/public/browser/content_browser_client.h

Index: content/public/browser/content_browser_client.h
diff --git a/content/public/browser/content_browser_client.h b/content/public/browser/content_browser_client.h
index 086731c4a2bb7572d25503e56271ecd14e54b769..4026ce59c24b0975524c0a93cacb7ca0eb00b35f 100644
--- a/content/public/browser/content_browser_client.h
+++ b/content/public/browser/content_browser_client.h
@@ -240,13 +240,22 @@ class CONTENT_EXPORT ContentBrowserClient {
       ResourceContext* context,
       const std::vector<std::pair<int, int> >& render_views);
 
-  // Allows the embedder to override the request context based on the URL for
+  // Allow the embedder to override the request context based on the URL for
   // certain operations, like cookie access. Returns NULL to indicate the
   // regular request context should be used.
   // This is called on the IO thread.
   virtual net::URLRequestContext* OverrideRequestContextForURL(
       const GURL& url, ResourceContext* context);
 
+  // Allow the embedder to specify which set of persistent state a child

[Charlie Reis, 2012/07/02 23:21:23]

I feel like "which set of persistent state" is leaving out some of our
expectations.  We're returning an ASCII ID that gets used for the directory name
on disk, right?  Maybe we need to be clearer about what's expected from the
ContentBrowserClient.

[awong, 2012/07/09 20:37:43]

I don't like adding information about how we implement storage on disk into this
API.  This seems to break the abstraction boundary.  Is the concern that we are
missing validation criteria for the id?  What if I say it should be ascii or
maybe even force it to be [a-z0-9]* (lowercase plus digits)?

[Charlie Reis, 2012/07/10 21:37:48]

That's sufficient.  Thanks.

+  // process should have access to.  Child processes that have different
+  // storage partition identifiers will behave as if they belong to different
+  // browser processes. Returns the empty string for the regular storage

[Charlie Reis, 2012/07/02 23:21:23]

browser processes -> web browsers

[awong, 2012/07/09 20:37:43]

Done.

+  // partition.
+  virtual std::string GetStoragePartitionForChildProcess(
+      content::BrowserContext* browser_context,
+      int child_process_id);
+
   // Create and return a new quota permission context.
   virtual QuotaPermissionContext* CreateQuotaPermissionContext();