Add default fonts for extensions

extensions/renderer/dispatcher.cc

Index: extensions/renderer/dispatcher.cc
diff --git a/extensions/renderer/dispatcher.cc b/extensions/renderer/dispatcher.cc
index c9aaec457060e951d8c0bae5a1e0731fd5505fc5..b48efd53dbb3ddc6af108a5d7f9188348c7d4f9c 100644
--- a/extensions/renderer/dispatcher.cc
+++ b/extensions/renderer/dispatcher.cc
@@ -325,20 +325,25 @@ void Dispatcher::WillReleaseScriptContext(
 }
 
 void Dispatcher::DidCreateDocumentElement(blink::WebFrame* frame) {
-  if (IsWithinPlatformApp()) {
-    // WebKit doesn't let us define an additional user agent stylesheet, so we
-    // insert the default platform app stylesheet into all documents that are
-    // loaded in each app.
-    std::string stylesheet = ResourceBundle::GetSharedInstance()
-                                 .GetRawDataResource(IDR_PLATFORM_APP_CSS)
-                                 .as_string();
+  if (IsWithinPlatformApp() || IsWithinExtension()) {

[not at google - send to devlin, 2014/07/19 00:08:10]

I don't think (looking at IsWithinExtension) this is quite right. If an
extension hosts an iframe for some page, that page shouldn't get the style of
the extension, but I think that's what will happen here.

likewise I think that IsWithinPlatformApp isn't right here either (though it's
unlikely to actually matter since apps can't host web content in-process). but
we might as well fix it:

const Extension* extension = extensions_->GetExtensionOrAppByURL(
    frame->document()->url());
if (extension) {
  ...
}

[not at google - send to devlin, 2014/07/19 00:19:24]

The URL shouldn't come from frame->document()->url() actually, since that won't
include about:blank URLs. Quite the corner case, but we should fix it:

// Note: use GetEffectiveDocumentURL not just frame->document()->url()
// so that this also injects the stylesheet on about:blank frames that
// are hosted in the extension process.
GURL effective_document_url = ScriptContext::GetEffectiveDocumentURL(
    frame, frame->docuemnt()->url(), true /* match_about_blank */);

[ericzeng, 2014/07/19 01:48:59]

Done.

+    std::string stylesheet;
+    if (IsWithinPlatformApp())
+      // WebKit doesn't let us define an additional user agent stylesheet, so we
+      // insert the default platform app stylesheet into all documents that are
+      // loaded in each app.
+      stylesheet = ResourceBundle::GetSharedInstance()
+                       .GetRawDataResource(IDR_PLATFORM_APP_CSS)
+                       .as_string();
+    else if (IsWithinExtension())
+      stylesheet = ResourceBundle::GetSharedInstance()
+                       .GetRawDataResource(IDR_EXTENSION_CSS)
+                       .as_string();

[not at google - send to devlin, 2014/07/19 00:08:10]

each of these has multi-line bodies; use {}.

though it'd be simpler to write

int resource_id = IsWithinPlatformApp() ?
    IDR_PLATFORM_APP_CSS : IDR_EXTENSION_CSS;
...

[ericzeng, 2014/07/19 01:48:59]

Is there a case where the renderer could host something other than an extension
or platform app? 

[not at google - send to devlin, 2014/07/19 01:54:16]

oh, right. yes :) good point.

     ReplaceFirstSubstringAfterOffset(
         &stylesheet, 0, "$FONTFAMILY", system_font_family_);
     ReplaceFirstSubstringAfterOffset(
         &stylesheet, 0, "$FONTSIZE", system_font_size_);
     frame->document().insertStyleSheet(WebString::fromUTF8(stylesheet));
   }
-
   content_watcher_->DidCreateDocumentElement(frame);
 }
 
@@ -1068,6 +1073,17 @@ bool Dispatcher::IsWithinPlatformApp() {
   return false;
 }
 
+bool Dispatcher::IsWithinExtension() {
+  for (std::set<std::string>::iterator iter = active_extension_ids_.begin();
+       iter != active_extension_ids_.end();
+       ++iter) {
+    const Extension* extension = extensions_.GetByID(*iter);
+    if (extension && extension->is_extension())
+      return true;
+  }
+  return false;
+}
+
 // TODO(kalman): This is checking for the wrong thing, it should be checking if
 // the frame's security origin is unique. The extension sandbox directive is
 // checked for in extensions/common/manifest_handlers/csp_info.cc.