DevTools: request page thumbnails from the devtools handler delegate, do not redirect to chrome://t…

content/public/browser/devtools_http_handler_delegate.h

Index: content/public/browser/devtools_http_handler_delegate.h
diff --git a/content/public/browser/devtools_http_handler_delegate.h b/content/public/browser/devtools_http_handler_delegate.h
index 4ff7058f03f23d33db56172bcbb56dfe6fdc8be6..36c3b07f086c3e00e8d2b02c5bc6a6bfbb7eb74d 100644
--- a/content/public/browser/devtools_http_handler_delegate.h
+++ b/content/public/browser/devtools_http_handler_delegate.h
@@ -8,6 +8,8 @@
 #include <string>
 #include <vector>
 
+class GURL;
+
 namespace content {
 
 class WebContents;
@@ -26,6 +28,10 @@ class DevToolsHttpHandlerDelegate {
   // Returns URL that front-end files are available at, empty string if
   // no internal server is available.
   virtual std::string GetFrontendResourcesBaseURL() = 0;
+
+  // Get a thumbnail for a given page. Returns non-empty string iff we have the
+  // thumbnail.
+  virtual std::string GetPageThumbnailData(const GURL& url) = 0;
 };
 
 }  // namespace content