Fix window.open issue in Document mode on Android.

Defers unblocking renderer's requests until the asynchronous activity
and tab loading process is complete and we are ready to handle
additional requests.

Adds new android-specific API to resume the requests and web contents
delegate API to allow the deferral for resuming renderer request
handling.

BUG=432562

Review URL: https://codereview.chromium.org/1095913002

Cr-Commit-Position: refs/heads/master@{#327414}
diff --git a/content/public/browser/web_contents.h b/content/public/browser/web_contents.h
index 4380412..d6c9a96 100644
--- a/content/public/browser/web_contents.h
+++ b/content/public/browser/web_contents.h
@@ -628,6 +628,13 @@
   // Requests the renderer to exit fullscreen.
   virtual void ExitFullscreen() = 0;
 
+  // Unblocks requests from renderer for a newly created window. This is
+  // used in showCreatedWindow() or sometimes later in cases where
+  // delegate->ShouldResumeRequestsForCreatedWindow() indicated the requests
+  // should not yet be resumed. Then the client is responsible for calling this
+  // as soon as they are ready.
+  virtual void ResumeLoadingCreatedWebContents() = 0;
+
 #if defined(OS_ANDROID)
   CONTENT_EXPORT static WebContents* FromJavaWebContents(
       jobject jweb_contents_android);