Allow content script insertion on about:-URLs.

chrome/renderer/extensions/user_script_slave.cc

Index: chrome/renderer/extensions/user_script_slave.cc
diff --git a/chrome/renderer/extensions/user_script_slave.cc b/chrome/renderer/extensions/user_script_slave.cc
index bdaff10bb86692bbe69c3f3e69cadc438f90067c..6b89753ac0f66874ab2c417371d21df9c2eefef2 100644
--- a/chrome/renderer/extensions/user_script_slave.cc
+++ b/chrome/renderer/extensions/user_script_slave.cc
@@ -38,6 +38,7 @@
 #include "url/gurl.h"
 
 using blink::WebFrame;
+using blink::WebDocument;
 using blink::WebSecurityOrigin;
 using blink::WebSecurityPolicy;
 using blink::WebString;
@@ -194,6 +195,38 @@ GURL UserScriptSlave::GetDataSourceURLForFrame(const WebFrame* frame) {
   return GURL(data_source->request().url());
 }
 
+GURL UserScriptSlave::GetEffectiveDocumentURL(const WebFrame* frame,
+                                              const GURL& document_url,
+                                              bool match_about_blank) {
+  if (!match_about_blank || !document_url.SchemeIs(content::kAboutScheme))
+    return document_url;
+
+  // Scripts on about:blank and about:srcdoc can access their parent document,
+  // so traverse the document tree until a non-about:blank frame is found.
+  WebDocument originDocument = frame->document();
+  const WebSecurityOrigin securityOrigin = originDocument.securityOrigin();

[not at google - send to devlin, 2014/05/01 20:32:19]

security_origin

[robwu, 2014/05/01 21:30:38]

Done. Should I also use underscores for |parentDocument| and
|parentDocumentUrl|?

[not at google - send to devlin, 2014/05/02 16:01:48]

yep, thanks. always underscore style in Chromium (unless forced to camel case to
implement a Blink API).

+  WebFrame* parent = frame->parent() ? frame->parent() : frame->opener();

[not at google - send to devlin, 2014/05/01 20:32:19]

nit: this big block is hard to read, perhaps a blank line here will help

+  // Note: The next loop body is usually run at most once. It is only repeated
+  // when an about:-frame is embedded in another about:-frame.
+  while (parent != NULL) {

[not at google - send to devlin, 2014/05/01 20:32:19]

i think this loop, whole function really, could be simpler if this condition
were document_url.SchemeIs(content::kAboutScheme). you should only need to check
that once (not twice) and you should only really need to get the parent/opener
document once. i would find the logic here a bit easier to follow in that case.

+    WebDocument parentDocument = parent->document();
+    // Immediately stop traversing the document hierarchy when the page does
+    // not have the permission to access its parent document.
+    if (!securityOrigin.canAccess(parentDocument.securityOrigin()))
+      return document_url;
+
+    // Return the first accessible non-about: URL if found.
+    GURL parentDocumentUrl(parentDocument.url());
+    if (!parentDocumentUrl.SchemeIs(content::kAboutScheme))
+      return parentDocumentUrl;
+
+    originDocument = parentDocument;

[not at google - send to devlin, 2014/05/01 20:32:19]

you don't use this variable inside nor after the loop, so this assignment is
unnecessary.

so storing originDocument in a variable rather than just securityOrigin is
unnecessary.

+    parent = parent->parent() ? parent->parent() : parent->opener();
+  }
+  // A standalone top-level document, just return the original URL.
+  return document_url;
+}
+
 void UserScriptSlave::InjectScripts(WebFrame* frame,
                                     UserScript::RunLocation location) {
   GURL data_source_url = GetDataSourceURLForFrame(frame);
@@ -224,12 +257,15 @@ void UserScriptSlave::InjectScripts(WebFrame* frame,
     if (!extension)
       continue;
 
+    const GURL& document_url = GetEffectiveDocumentURL(
+        frame, data_source_url, script->match_about_blank());
+
     // Content scripts are not tab-specific.
     const int kNoTabId = -1;
     // We don't have a process id in this context.
     const int kNoProcessId = -1;
     if (!PermissionsData::CanExecuteScriptOnPage(extension,
-                                                 data_source_url,
+                                                 document_url,
                                                  frame->top()->document().url(),
                                                  kNoTabId,
                                                  script,