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..e7b8d183bc94ddb5465f9a6d0cd3c01e0e00c142 100644
--- a/extensions/renderer/dispatcher.cc
+++ b/extensions/renderer/dispatcher.cc
@@ -325,21 +325,35 @@ 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();
-    ReplaceFirstSubstringAfterOffset(
-        &stylesheet, 0, "$FONTFAMILY", system_font_family_);
-    ReplaceFirstSubstringAfterOffset(
-        &stylesheet, 0, "$FONTSIZE", system_font_size_);
-    frame->document().insertStyleSheet(WebString::fromUTF8(stylesheet));
+  // 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->document().url(), true /* match_about_blank */);
+  const Extension* extension =
+      extensions_.GetExtensionOrAppByURL(effective_document_url);
+  if (extension) {

[not at google - send to devlin, 2014/07/21 16:44:23]

given the whole rest of this method is inside this if-block, perhaps reverse the
condition and early-return instead.

[ericzeng, 2014/07/21 18:12:33]

Done.

+    if (extension->is_extension() || extension->is_platform_app()) {
+      std::string stylesheet;
+      if (extension->is_platform_app())
+        // 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.

[not at google - send to devlin, 2014/07/21 16:44:23]

this comment belongs before the "insertStyleSheet" call.

[ericzeng, 2014/07/21 18:12:33]

Done.

+        stylesheet = ResourceBundle::GetSharedInstance()
+                         .GetRawDataResource(IDR_PLATFORM_APP_CSS)

[not at google - send to devlin, 2014/07/21 16:44:23]

it would be simpler to switch on the resource ID rather than the resource. then
you can also use ternary and this block becomes even simpler.

[ericzeng, 2014/07/21 18:12:33]

What do you mean by switching on the resource ID?

No ternary operator!
https://codereview.chromium.org/400343002/diff/1/extensions/renderer/dispatch...

[not at google - send to devlin, 2014/07/21 18:31:29]

Ternary operator is fine here because the block is guarded on 
(extension->is_extension() || extension->is_platform_app()).

and "by switching on the resource ID" I mean, basically the code I wrote in that
comment you just linked to.

[ericzeng, 2014/07/21 18:43:11]

Got it, but I'll use extension->is_platform_app() rather than
IsWithinPlatformApp().

+                         .as_string();
+      else if (extension->is_extension())
+        stylesheet = ResourceBundle::GetSharedInstance()
+                         .GetRawDataResource(IDR_EXTENSION_CSS)
+                         .as_string();
+      ReplaceFirstSubstringAfterOffset(
+          &stylesheet, 0, "$FONTFAMILY", system_font_family_);
+      ReplaceFirstSubstringAfterOffset(
+          &stylesheet, 0, "$FONTSIZE", system_font_size_);
+      frame->document().insertStyleSheet(WebString::fromUTF8(stylesheet));
+    }
+    content_watcher_->DidCreateDocumentElement(frame);

[not at google - send to devlin, 2014/07/21 16:44:23]

(note: moving this inside the if-block is a change in behaviour, though it's
more correct now, so... cool)

   }
-
-  content_watcher_->DidCreateDocumentElement(frame);
 }
 
 void Dispatcher::DidMatchCSS(