Add support for parsing a 'partition' attribute on the <browser> tag.

content/renderer/browser_plugin/browser_plugin.cc

Index: content/renderer/browser_plugin/browser_plugin.cc
diff --git a/content/renderer/browser_plugin/browser_plugin.cc b/content/renderer/browser_plugin/browser_plugin.cc
index 8ba5421f33aa700fe63e733024d9a5185ed74684..e144b3d3e7f3bbf979f4b1a9ecb5b6eaae0b9f16 100644
--- a/content/renderer/browser_plugin/browser_plugin.cc
+++ b/content/renderer/browser_plugin/browser_plugin.cc
@@ -6,6 +6,7 @@
 
 #include "base/message_loop.h"
 #include "base/string_util.h"
+#include "base/utf_string_conversions.h"
 #include "content/common/browser_plugin_messages.h"
 #include "content/public/common/content_client.h"
 #include "content/public/renderer/content_renderer_client.h"
@@ -40,6 +41,7 @@ namespace {
 const char kCrashEventName[] = "crash";
 const char kNavigationEventName[] = "navigation";
 const char* kSrcAttribute = "src";
+const char* kPartitionAttribute = "partition";
 }
 
 BrowserPlugin::BrowserPlugin(
@@ -54,13 +56,13 @@ BrowserPlugin::BrowserPlugin(
       sad_guest_(NULL),
       guest_crashed_(false),
       resize_pending_(false),
-      parent_frame_(frame->identifier()) {
+      parent_frame_(frame->identifier()),
+      has_navigated_(false),
+      persist_storage_(false) {
   BrowserPluginManager::Get()->AddBrowserPlugin(instance_id, this);
   bindings_.reset(new BrowserPluginBindings(this));
 
-  std::string src;
-  if (ParseSrcAttribute(params, &src))
-    SetSrcAttribute(src);
+  ParseAttributes(params);
 }
 
 BrowserPlugin::~BrowserPlugin() {
@@ -97,23 +99,75 @@ void BrowserPlugin::SetSrcAttribute(const std::string& src) {
             instance_id_,
             parent_frame_,
             src));
+    has_navigated_ = true;
   }
   src_ = src;
   guest_crashed_ = false;
 }
 
-bool BrowserPlugin::ParseSrcAttribute(
-    const WebKit::WebPluginParams& params,
-    std::string* src) {
+std::string BrowserPlugin::GetPartitionAttribute() const {
+  std::string value;
+  if (persist_storage_)
+    value.append("persist:");

[Charlie Reis, 2012/09/18 22:09:33]

This should be a constant at the top of the file.

[nasko, 2012/09/18 22:56:20]

Done.

+
+  value.append(storage_partition_id_);
+  return value;
+}
+
+bool BrowserPlugin::SetPartitionAttribute(const std::string& partition_id,
+                                          std::string& error_message) {
+  if (has_navigated_) {
+    error_message = "The object has already navigated.";

[Charlie Reis, 2012/09/18 22:09:33]

Can we provide a little more to help the developer?  e.g., (", so its partition
ID cannot be changed.")

[nasko, 2012/09/18 22:56:20]

Done.

+    return false;
+  }
+  if (!storage_partition_id_.empty()) {
+    error_message = "The partition attribute has already been set.";

[Charlie Reis, 2012/09/18 22:09:33]

Why is this an error?  Couldn't you safely set it to multiple values before the
first navigation?

[nasko, 2012/09/18 22:56:20]

I would like to disallow setting it multiple times. It will be consistent with
navigation and the rule can be simple - you can only set the partition attribute
once.

[Charlie Reis, 2012/09/19 00:06:31]

That seems like an unnecessary restriction to me, and I don't agree with that
way of stating the rule.  ("You can only set the partition attribute once" would
allow setting it once after the first navigation.)

To me, the rule is "you can only set the partition attribute before the first
navigation," which implies you can set it as many times as you want until then.

That said, I can't think of a case it would matter.  Also, I suppose it's easier
to loosen the restriction later (if people object) than to add it.  So I'm ok
with leaving it if you want the rule to be "you can only set the partition once,
and only before the first navigation."

[nasko, 2012/09/19 17:03:23]

Done.

+    return false;
+  }
+
+  std::string input = partition_id;
+  std::string persist_prefix("persist:");
+
+  // Since the "persist:" prefix is in ASCII, StartsWith will work fine on
+  // UTF-8 encoded |partition_id|. If the prefix is a match, we can safely
+  // remove the prefix without splicing in the middle of a multi-byte codepoint.
+  // We can use the rest of the string as UTF-8 encoded one.

[Charlie Reis, 2012/09/18 22:09:33]

Awesome comment.

[nasko, 2012/09/18 22:56:20]

Credit goes to the master of awesomeness - ajwong!

+  if (StartsWithASCII(input, persist_prefix, true)) {
+    size_t index = input.find(":");
+    CHECK(index != std::string::npos);
+    // It is safe to do index + 1, since we tested for the full prefix above.
+    input = input.substr(index + 1);
+    if (input.empty()) {
+      error_message = "Invalid partition attribute.";

[Charlie Reis, 2012/09/18 22:09:33]

Maybe "Invalid empty partition attribute"?  This is the "persist:" case, right?

[nasko, 2012/09/18 22:56:20]

Done.

+      return false;
+    }
+    persist_storage_ = true;
+  } else {
+    persist_storage_ = false;
+  }
+
+  storage_partition_id_ = input;
+  return true;
+}
+
+void BrowserPlugin::ParseAttributes(const WebKit::WebPluginParams& params) {
+  std::string src;
+
   // Get the src attribute from the attributes vector
   for (unsigned i = 0; i < params.attributeNames.size(); ++i) {
     std::string attributeName = params.attributeNames[i].utf8();
     if (LowerCaseEqualsASCII(attributeName, kSrcAttribute)) {
-      *src = params.attributeValues[i].utf8();
-      return true;
+      src = params.attributeValues[i].utf8();
+    } else if (LowerCaseEqualsASCII(attributeName, kPartitionAttribute)) {
+      std::string error;
+      SetPartitionAttribute(params.attributeValues[i].utf8(), error);
     }
   }
-  return false;
+
+  // Set the 'src' attribute last, as it will set the has_navigated_ flag to
+  // true, which prevents changing the 'partition' attribute.

[Charlie Reis, 2012/09/18 22:09:33]

Ah, good point.

[nasko, 2012/09/18 22:56:20]

Done.

+  if (!src.empty())
+    SetSrcAttribute(src);
 }
 
 float BrowserPlugin::GetDeviceScaleFactor() const {