Use black for resize gutter in tab fullscreen mode.

content/browser/renderer_host/delegated_frame_host.h

Index: content/browser/renderer_host/delegated_frame_host.h
diff --git a/content/browser/renderer_host/delegated_frame_host.h b/content/browser/renderer_host/delegated_frame_host.h
index 66b0ac29978c6eff8f1aa002acd80fd590775111..6b4ae2d82312a54715cfc3e6778c4148f04d77e2 100644
--- a/content/browser/renderer_host/delegated_frame_host.h
+++ b/content/browser/renderer_host/delegated_frame_host.h
@@ -55,6 +55,10 @@ class CONTENT_EXPORT DelegatedFrameHostClient {
  public:
   virtual ui::Layer* DelegatedFrameHostGetLayer() const = 0;
   virtual bool DelegatedFrameHostIsVisible() const = 0;
+
+  // The callee can change the value of *color to modify what color the resize
+  // gutters are drawn with.
+  virtual void DelegatedFrameHostOverrideGutterColor(SkColor* color) const = 0;
   virtual gfx::Size DelegatedFrameHostDesiredSizeInDIP() const = 0;
 
   virtual bool DelegatedFrameCanCreateResizeLock() const = 0;
@@ -203,6 +207,8 @@ class CONTENT_EXPORT DelegatedFrameHost
   // Checks if the resize lock can be released because we received an new frame.
   void CheckResizeLock();
 
+  SkColor GetGutterColor() const;
+
   // Update the layers for the resize gutters to the right and bottom of the
   // surface layer.
   void UpdateGutters();