Expose IsWaitingToCommit() on NavigationHandle

Currently, it is only defined on NavigationRequests. Defining it on
the handles too will allow for easy determination of when a navigation
has passed through ReadyToCommitNavigation(), i.e. via HasCommitted() ||
IsWaitingToCommit(). Note that some navigations can pass through
ReadyToCommitNavigation() without eventually committing -- e.g. due to a
doc.write. Adding this call will simplify handling of these edge cases.

Bug: 1101584
Change-Id: I7c272ef2768a901b8988bfe8e28ae1a0c3ef2ca9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2536389Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Alex Turner <alexmt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827933}

content/browser/renderer_host/navigation_request.h

@@ -325,6 +325,7 @@ class CONTENT_EXPORT NavigationRequest
   bool GetIsOverridingUserAgent() override;
   void SetSilentlyIgnoreErrors() override;
   network::mojom::WebSandboxFlags SandboxFlagsToCommit() override;
+  bool IsWaitingToCommit() override;
 
   // Called on the UI thread by the Navigator to start the navigation.
   // The NavigationRequest can be deleted while BeginNavigation() is called.
@@ -684,11 +685,6 @@ class CONTENT_EXPORT NavigationRequest
   // Returns the coop status information relevant to the current navigation.
   CrossOriginOpenerPolicyStatus& coop_status() { return coop_status_; }
 
-  // Whether the navigation was sent to be committed in a renderer by the
-  // RenderFrameHost. This can either be for the commit of a successful
-  // navigation or an error page.
-  bool IsWaitingToCommit();
-
   // Returns true if |url| and |base_url| represent a WebView
   // loadDataWithBaseUrl navigation.
   static bool IsLoadDataWithBaseURL(const GURL& url, const GURL& base_url);

content/public/browser/navigation_handle.h

@@ -426,6 +426,11 @@ class CONTENT_EXPORT NavigationHandle {
   // directly into the RenderDocumentHost.
   virtual network::mojom::WebSandboxFlags SandboxFlagsToCommit() = 0;
 
+  // Whether the navigation was sent to be committed in a renderer by the
+  // RenderFrameHost. This can either be for the commit of a successful
+  // navigation or an error page.
+  virtual bool IsWaitingToCommit() = 0;
+
   // Testing methods ----------------------------------------------------------
   //
   // The following methods should be used exclusively for writing unit tests.

content/public/test/mock_navigation_handle.h

@@ -143,6 +143,7 @@ class MockNavigationHandle : public NavigationHandle {
   MOCK_METHOD(bool, GetIsOverridingUserAgent, ());
   MOCK_METHOD(void, SetSilentlyIgnoreErrors, ());
   MOCK_METHOD(network::mojom::WebSandboxFlags, SandboxFlagsToCommit, ());
+  MOCK_METHOD(bool, IsWaitingToCommit, ());
 
   void set_url(const GURL& url) { url_ = url; }
   void set_previous_url(const GURL& previous_url) {