blimp: Update page load status update indicator to use first paint.

blimp/engine/session/blimp_engine_session.h

Index: blimp/engine/session/blimp_engine_session.h
diff --git a/blimp/engine/session/blimp_engine_session.h b/blimp/engine/session/blimp_engine_session.h
index a78bb664c4b7a560cf1ca9a07c75f8b76be33b11..3f66f5d2abdbcd7e5bc240735851d4d22e3f489d 100644
--- a/blimp/engine/session/blimp_engine_session.h
+++ b/blimp/engine/session/blimp_engine_session.h
@@ -14,6 +14,7 @@
 #include "blimp/common/proto/blimp_message.pb.h"
 #include "blimp/engine/feature/engine_render_widget_feature.h"
 #include "blimp/engine/feature/engine_settings_feature.h"
+#include "blimp/engine/session/page_load_tracker.h"
 #include "blimp/net/blimp_message_processor.h"
 #include "blimp/net/connection_error_observer.h"
 #include "content/public/browser/invalidate_type.h"
@@ -72,7 +73,8 @@ class BlimpEngineSession
       public content::WebContentsDelegate,
       public content::WebContentsObserver,
       public ui::InputMethodObserver,
-      public EngineRenderWidgetFeature::RenderWidgetMessageDelegate {
+      public EngineRenderWidgetFeature::RenderWidgetMessageDelegate,
+      public PageLoadTrackerClient {
  public:
   BlimpEngineSession(std::unique_ptr<BlimpBrowserContext> browser_context,
                      net::NetLog* net_log,
@@ -141,8 +143,6 @@ class BlimpEngineSession
       const std::vector<uint8_t>& proto) override;
   void NavigationStateChanged(content::WebContents* source,
                               content::InvalidateTypes changed_flags) override;
-  void LoadProgressChanged(content::WebContents* source,
-                           double progress) override;
 
   // ui::InputMethodObserver overrides.
   void OnTextInputTypeChanged(const ui::TextInputClient* client) override;
@@ -158,14 +158,27 @@ class BlimpEngineSession
   void RenderViewHostChanged(content::RenderViewHost* old_host,
                              content::RenderViewHost* new_host) override;
   void RenderViewDeleted(content::RenderViewHost* render_view_host) override;
+  void DidStartProvisionalLoadForFrame(
+      content::RenderFrameHost* render_frame_host,
+      const GURL& validated_url,
+      bool is_error_page,
+      bool is_iframe_srcdoc) override;
+  void DidFinishLoad(content::RenderFrameHost* render_frame_host,
+                     const GURL& validated_url) override;
+  void DidFailLoad(content::RenderFrameHost* render_frame_host,
+                   const GURL& validated_url,
+                   int error_code,
+                   const base::string16& error_description,
+                   bool was_ignored_by_handler) override;
+  void DidFirstPaintAfterLoad(
+      content::RenderWidgetHost* render_widget_host) override;
+
+  // PageLoadTrackerClient implementation.
+  void SendPageLoadStatusUpdate(bool load_status) override;
 
   // Sets up and owns |new_contents|.
   void PlatformSetContents(std::unique_ptr<content::WebContents> new_contents);
 
-  // Stores the value of the last page load completed update sent to the client.
-  // This field is used per tab.
-  bool last_page_load_completed_value_;
-
   // Content BrowserContext for this session.
   std::unique_ptr<BlimpBrowserContext> browser_context_;
 
@@ -202,6 +215,9 @@ class BlimpEngineSession
   // including INPUT, COMPOSITOR and RENDER_WIDGET messages.
   EngineRenderWidgetFeature render_widget_feature_;
 
+  // Tracks the page load status for a tab.
+  PageLoadTracker page_load_tracker_;
+
   // Container for connection manager, authentication handler, and
   // browser connection handler. The components run on the I/O thread, and
   // this object is destroyed there.