[Script Injection] Allow whitelisted extensions to inject scripts eve…

…rywhere

Fix a regression where whitelisted extensions couldn't inject content scripts on
other extension pages.

BUG=517370
TBR=kalman@chromium.org

Review URL: https://codereview.chromium.org/1294393003

Cr-Commit-Position: refs/heads/master@{#345382}
(cherry picked from commit 29d2ec9)

Review URL: https://codereview.chromium.org/1319143004 .

Cr-Commit-Position: refs/branch-heads/2490@{#185}
Cr-Branched-From: 7790a35-refs/heads/master@{#344925}

extensions/renderer/extension_injection_host.cc

@@ -57,8 +57,10 @@ PermissionsData::AccessType ExtensionInjectionHost::CanExecuteOnFrame(
 
   blink::WebSecurityOrigin top_frame_security_origin =
       render_frame->GetWebFrame()->top()->securityOrigin();
+  // Only whitelisted extensions may run scripts on another extension's page.
   if (top_frame_security_origin.protocol().utf8() == kExtensionScheme &&
-      top_frame_security_origin.host().utf8() != extension_->id())
+      top_frame_security_origin.host().utf8() != extension_->id() &&
+      !PermissionsData::CanExecuteScriptEverywhere(extension_))
     return PermissionsData::ACCESS_DENIED;
 
   // Declarative user scripts use "page access" (from "permissions" section in