Add basic support to dump pixel results

content/shell/layout_test_controller_host.h

Index: content/shell/layout_test_controller_host.h
diff --git a/content/shell/layout_test_controller_host.h b/content/shell/layout_test_controller_host.h
index 733dfc9c8dc9b5c88670d9d9082a6fb170113ad5..f078608d9051474651fd3f037a017c0021d9e5bb 100644
--- a/content/shell/layout_test_controller_host.h
+++ b/content/shell/layout_test_controller_host.h
@@ -11,6 +11,8 @@
 
 #include "content/public/browser/render_view_host_observer.h"
 
+class SkBitmap;
+
 namespace content {
 
 class LayoutTestControllerHost : public RenderViewHostObserver {
@@ -18,6 +20,9 @@ class LayoutTestControllerHost : public RenderViewHostObserver {
   static LayoutTestControllerHost* FromRenderViewHost(
       RenderViewHost* render_view_host);
 
+  // Initialize the LayoutTestControllerHost for a given test.
+  static void Init(const std::string& expected_pixel_hash);
+
   explicit LayoutTestControllerHost(RenderViewHost* render_view_host);
   virtual ~LayoutTestControllerHost();
 
@@ -34,6 +39,7 @@ class LayoutTestControllerHost : public RenderViewHostObserver {
   // Message handlers.
   void OnDidFinishLoad();
   void OnTextDump(const std::string& dump);
+  void OnImageDump(const SkBitmap& image);
 
   // layoutTestController handlers.
   void OnNotifyDone();
@@ -44,6 +50,7 @@ class LayoutTestControllerHost : public RenderViewHostObserver {
   void OnWaitUntilDone();
 
   static std::map<RenderViewHost*, LayoutTestControllerHost*> controllers_;
+  static std::string expected_pixel_hash_;
 
   bool dump_as_text_;
   bool dump_child_frames_;