Adding component extension with background page in Chromium does not work.

[Viatcheslav Gachkaylo]

Hello.

I want to add a component extension to Chromium release 12.0.742.100
I've added "key" attribute to extension's manifest properly.
I've added a folder with an extension to chrome/browser/resources.
Added resource for manifest in chrome/browser/browser_resources.grd
with path: resources\uncensor\manifest.json
Added all extension files to chrome/browser/resources/
component_extension_resources.grd
with path: uncensor/filename.ext
And added this code to chrome/browser/profiles/profile_impl.cc:

component_extensions.push_back(std::make_pair(
FILE_PATH_LITERAL("uncensor"),
IDR_UNCENSOR_MANIFEST));

Also I've changed the ShouldShowExtension return result to true for
component extensions, so that I see them when I open chrome://extensions

And when I click on background.html in chrome://extensions (developer
mode) to see the page with my extension - I get Resource not found in
javascript console and I see a blank page. Can you suggest where can I
look at to fix this issue and make background page load?

I've tested the extension without adding it to browser resources and
it works ok.

[Antony Sargent]

I'd try putting a breakpoint in ExtensionsDOMHandler::HandleInspectMessage and step through the debugger from there (maybe try with a normal extension first, then your component one to see where things differ). 

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[Viatcheslav Gachkaylo]

After debugging for a while, I've found that the actual problem is with extension controlled preference, which I added before.
In chrome/browser/extensions/extension_preference_api.cc I've added my property to the list

PrefMappingEntry kPrefMapping[] = {
{ "blockThirdPartyCookies",
prefs::kBlockThirdPartyCookies,
Extension::kContentSettingsPermission
},
{ "enableReferrers",
prefs::kEnableReferrers,
Extension::kContentSettingsPermission
},
{ "enableHyperlinkAuditing",
prefs::kEnableHyperlinkAuditing,
Extension::kContentSettingsPermission
},
{ "proxy",
prefs::kProxy,
Extension::kProxyPermission
},
+ { "uncensorPrefs",
+ prefs::kUncensorPrefs,
+ Extension::kContentSettingsPermission
+ },
};

Also I've changed the json file with api description, adding uncensorPrefs to chrome.experimental.contentSettings.misc.uncensorPrefs
and registered the preference, initializing it with empty string.
Also my component extension has permissions "experimental" and "contentSettings"

But I probably missed something required to access property from extension.
What else might I need to enable access to this property from a component extension?

Thank you,
Viatcheslav Gachkaylo
Crystalnix

[Viatcheslav Gachkaylo]

The browser fails on startup in chrome/browser/extensions/extension_pref_value_map.cc:

bool ExtensionPrefValueMap::CanExtensionControlPref(
const std::string& extension_id,
const std::string& pref_key,
bool incognito) const {
ExtensionEntryMap::const_iterator ext = entries_.find(extension_id);
if (ext == entries_.end()) {
NOTREACHED(); <-- fails here
return false;

[Mattias Nissler]

Dominic, I figured you'd now about this particular NOTREACHED() :)

[Viatcheslav Gachkaylo]

One strange thing happen. If I don't use "key" attribute in extension's manifest.json and load it from a local folder -

everything works as expected. Does it mean component extensions are not allowed to access experimental

or contentSettings API?

[Dominic Battre]

You need to register the preference first for this to work. Registering the extension defines the type of values that can be stored as well as a default value.

Please check chrome/browser/prefs/browser_prefs.cc and add your preference registration to RegisterUserPrefs.

Dominic

[Viatcheslav Gachkaylo]

I had a line:

prefs->RegisterStringPref(prefs::kUncensorPrefs, std::string());

in chrome/browser/ui/browser.cc

If I hadn't this property registered - the extension wouldn't work when running from a local folder. The problem persists when adding a "key" attribute for public key and running as a component extension.

Thank you,

Viatcheslav Gachkaylo