Plumb first contentful paint notification to WebLayer Java API.

This is needed for embedders to calculate metrics.

Change-Id: Id804dab8eea8e55eebdde52f0aa44157e9a7be5f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1869339
Commit-Queue: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#707938}

weblayer/browser/browser_controller_impl.cc

@@ -238,11 +238,6 @@ blink::mojom::DisplayMode BrowserControllerImpl::GetDisplayMode(
                         : blink::mojom::DisplayMode::kBrowser;
 }
 
-void BrowserControllerImpl::DidFirstVisuallyNonEmptyPaint() {
-  for (auto& observer : observers_)
-    observer.FirstContentfulPaint();
-}
-
 void BrowserControllerImpl::DidFinishNavigation(
     content::NavigationHandle* navigation_handle) {
 #if defined(OS_ANDROID)

weblayer/browser/browser_controller_impl.h

@@ -95,7 +95,6 @@ class BrowserControllerImpl : public BrowserController,
       const content::WebContents* web_contents) override;
 
   // content::WebContentsObserver:
-  void DidFirstVisuallyNonEmptyPaint() override;
   void DidFinishNavigation(
       content::NavigationHandle* navigation_handle) override;
 

weblayer/browser/browser_observer_proxy.cc

@@ -46,8 +46,6 @@ void BrowserObserverProxy::LoadProgressChanged(double progress) {
   Java_BrowserObserverProxy_loadProgressChanged(env, java_observer_, progress);
 }
 
-void BrowserObserverProxy::FirstContentfulPaint() {}
-
 static jlong JNI_BrowserObserverProxy_CreateBrowserObserverProxy(
     JNIEnv* env,
     const base::android::JavaParamRef<jobject>& proxy,

weblayer/browser/browser_observer_proxy.h

@@ -29,7 +29,6 @@ class BrowserObserverProxy : public BrowserObserver {
   void LoadingStateChanged(bool is_loading,
                            bool to_different_document) override;
   void LoadProgressChanged(double progress) override;
-  void FirstContentfulPaint() override;
 
  private:
   BrowserController* browser_controller_;

weblayer/browser/java/org/chromium/weblayer_private/NavigationControllerImpl.java

@@ -142,6 +142,15 @@ public final class NavigationControllerImpl extends INavigationController.Stub {
         }
     }
 
+    @CalledByNative
+    private void onFirstContentfulPaint() {
+        try {
+            mNavigationControllerClient.onFirstContentfulPaint();
+        } catch (RemoteException e) {
+            throw new APICallException(e);
+        }
+    }
+
     @NativeMethods
     interface Natives {
         void setNavigationControllerImpl(

weblayer/browser/java/org/chromium/weblayer_private/aidl/INavigationControllerClient.aidl

@@ -20,4 +20,6 @@ interface INavigationControllerClient {
   void navigationCompleted(IClientNavigation navigation) = 4;
 
   void navigationFailed(IClientNavigation navigation) = 5;
+
+  void onFirstContentfulPaint() = 6;
 }

weblayer/browser/navigation_controller_impl.cc

@@ -206,6 +206,16 @@ void NavigationControllerImpl::DidFinishNavigation(
   navigation_map_.erase(navigation_map_.find(navigation_handle));
 }
 
+void NavigationControllerImpl::DidFirstVisuallyNonEmptyPaint() {
+#if defined(OS_ANDROID)
+  Java_NavigationControllerImpl_onFirstContentfulPaint(AttachCurrentThread(),
+                                                       java_controller_);
+#endif
+
+  for (auto& observer : observers_)
+    observer.OnFirstContentfulPaint();
+}
+
 #if defined(OS_ANDROID)
 static jlong JNI_NavigationControllerImpl_GetNavigationController(
     JNIEnv* env,

weblayer/browser/navigation_controller_impl.h

@@ -91,6 +91,7 @@ class NavigationControllerImpl : public NavigationController,
       content::NavigationHandle* navigation_handle) override;
   void DidFinishNavigation(
       content::NavigationHandle* navigation_handle) override;
+  void DidFirstVisuallyNonEmptyPaint() override;
 
   BrowserControllerImpl* browser_controller_;
   base::ObserverList<NavigationObserver>::Unchecked observers_;

weblayer/public/browser_observer.h

@@ -27,10 +27,6 @@ class BrowserObserver {
   // corresponds to WebContentsDelegate::LoadProgressChanged, meaning |progress|
   // ranges from 0.0 to 1.0.
   virtual void LoadProgressChanged(double progress) {}
-
-  // This is fired after each navigation has completed, to indicate that the
-  // first paint after a non-empty layout has finished.
-  virtual void FirstContentfulPaint() {}
 };
 
 }  // namespace weblayer

weblayer/public/java/org/chromium/weblayer/NavigationController.java

@@ -165,5 +165,12 @@ public final class NavigationController {
                 observer.navigationFailed((Navigation) navigation);
             }
         }
+
+        @Override
+        public void onFirstContentfulPaint() {
+            for (NavigationObserver observer : mObservers) {
+                observer.onFirstContentfulPaint();
+            }
+        }
     }
 }

weblayer/public/java/org/chromium/weblayer/NavigationObserver.java

@@ -13,15 +13,85 @@ package org.chromium.weblayer;
  * 2) 0 or more navigationRedirected()
  * 3) 0 or 1 navigationCommitted()
  * 4) navigationCompleted() or navigationFailed()
+ * 5) onFirstContentfulPaint
  */
 public abstract class NavigationObserver {
+    /**
+     * Called when a navigation started in the BrowserController. |navigation| is unique to a
+     * specific navigation. The same |navigation| will be  provided on subsequent calls to
+     * NavigationRedirected, NavigationCommitted, NavigationCompleted and NavigationFailed when
+     * related to this navigation. Observers should clear any references to |navigation| in
+     * NavigationCompleted or NavigationFailed, just before it is destroyed.
+     *
+     * Note that this is only fired by navigations in the main frame.
+     *
+     * Note that this is fired by same-document navigations, such as fragment navigations or
+     * pushState/replaceState, which will not result in a document change. To filter these out, use
+     * Navigation::IsSameDocument.
+     *
+     * Note that more than one navigation can be ongoing in the BrowserController at the same time.
+     * Each will get its own Navigation object.
+     *
+     * Note that there is no guarantee that NavigationCompleted/NavigationFailed will be called for
+     * any particular navigation before NavigationStarted is called on the next.
+     *
+     * @param navigation the unique object for this navigation.
+     */
     public void navigationStarted(Navigation navigation) {}
 
+    /**
+     * Called when a navigation encountered a server redirect.
+     *
+     * @param navigation the unique object for this navigation.
+     */
     public void navigationRedirected(Navigation navigation) {}
 
+    /**
+     * Called when the navigation is ready to be committed in a renderer. A navigation is considered
+     * committed when the response code isn't 204/205 (which tell the browser that the request is
+     * successful but there's no content that follows) or a download (either from a response header
+     * or based on mime sniffing the response). The browser then is ready to switch rendering the
+     * new document. Most observers should use NavigationCompleted or NavigationFailed instead,
+     * which happens right after the navigation commits. This method is for observers that want to
+     * initialize renderer-side state just before the BrowserController commits the navigation.
+     *
+     * This is the first point in time where a BrowserController is associated with the navigation.
+     *
+     * @param navigation the unique object for this navigation.
+     */
     public void navigationCommitted(Navigation navigation) {}
 
+    /**
+     * Called when a navigation completes successfully in the BrowserController.
+     *
+     * The document load will still be ongoing in the BrowserController. Use the document loads
+     * events such as onFirstContentfulPaint and related methods to listen for continued events from
+     * this BrowserController.
+     *
+     * Note that this is fired by same-document navigations, such as fragment navigations or
+     * pushState/replaceState, which will not result in a document change. To filter these out, use
+     * NavigationHandle::IsSameDocument.
+     *
+     * Note that |navigation| will be destroyed at the end of this call, so do not keep a reference
+     * to it afterward.
+     *
+     * @param navigation the unique object for this navigation.
+     */
     public void navigationCompleted(Navigation navigation) {}
 
+    /**
+     * Called when a navigation aborts in the BrowserController.
+     *
+     * Note that |navigation| will be destroyed at the end of this call, so do not keep a reference
+     * to it afterward.
+     *
+     * @param navigation the unique object for this navigation.
+     */
     public void navigationFailed(Navigation navigation) {}
+
+    /**
+     * This is fired after each navigation has completed to indicate that the first paint after a
+     * non-empty layout has finished.
+     */
+    public void onFirstContentfulPaint() {}
 }

weblayer/public/navigation.h

@@ -34,6 +34,8 @@ class Navigation {
   };
 
   virtual State GetState() = 0;
+
+  // TODO(jam): add IsSameDocument
 };
 
 }  // namespace weblayer

weblayer/public/navigation_observer.h

@@ -20,15 +20,67 @@ class NavigationObserver {
  public:
   virtual ~NavigationObserver() {}
 
+  // Called when a navigation started in the BrowserController. |navigation| is
+  // unique to a specific navigation. The same |navigation| will be  provided on
+  // subsequent calls to NavigationRedirected, NavigationCommitted,
+  // NavigationCompleted and NavigationFailed when related to this navigation.
+  // Observers should clear any references to |navigation| in
+  // NavigationCompleted or NavigationFailed, just before it is destroyed.
+  //
+  // Note that this is only fired by navigations in the main frame.
+  //
+  // Note that this is fired by same-document navigations, such as fragment
+  // navigations or pushState/replaceState, which will not result in a document
+  // change. To filter these out, use Navigation::IsSameDocument.
+  //
+  // Note that more than one navigation can be ongoing in the BrowserController
+  // at the same time. Each will get its own Navigation object.
+  //
+  // Note that there is no guarantee that NavigationCompleted/NavigationFailed
+  // will be called for any particular navigation before NavigationStarted is
+  // called on the next.
   virtual void NavigationStarted(Navigation* navigation) {}
 
+  // Called when a navigation encountered a server redirect.
   virtual void NavigationRedirected(Navigation* navigation) {}
 
+  // Called when the navigation is ready to be committed in a renderer. A
+  // navigation is considered committed when the response code isn't 204/205
+  // (which tell the browser that the request is successful but there's no
+  // content that follows) or a download (either from a response header or based
+  // on mime sniffing the response). The browser then is ready to switch
+  // rendering the new document. Most observers should use NavigationCompleted
+  // or NavigationFailed instead, which happens right after the navigation
+  // commits. This method is for observers that want to initialize renderer-side
+  // state just before the BrowserController commits the navigation.
+  //
+  // This is the first point in time where a BrowserController is associated
+  // with the navigation.
   virtual void NavigationCommitted(Navigation* navigation) {}
 
+  // Called when a navigation completes successfully in the BrowserController.
+  //
+  // The document load will still be ongoing in the BrowserController. Use the
+  // document loads events such as OnFirstContentfulPaint and related methods to
+  // listen for continued events from this BrowserController.
+  //
+  // Note that this is fired by same-document navigations, such as fragment
+  // navigations or pushState/replaceState, which will not result in a document
+  // change. To filter these out, use NavigationHandle::IsSameDocument.
+  //
+  // Note that |navigation| will be destroyed at the end of this call, so do not
+  // keep a reference to it afterward.
   virtual void NavigationCompleted(Navigation* navigation) {}
 
+  // Called when a navigation aborts in the BrowserController.
+  //
+  // Note that |navigation| will be destroyed at the end of this call, so do not
+  // keep a reference to it afterward.
   virtual void NavigationFailed(Navigation* navigation) {}
+
+  // This is fired after each navigation has completed to indicate that the
+  // first paint after a non-empty layout has finished.
+  virtual void OnFirstContentfulPaint() {}
 };
 
 }  // namespace weblayer

weblayer/shell/android/javatests/src/org/chromium/weblayer/test/NavigationTest.java

@@ -57,6 +57,7 @@ public class NavigationTest {
         public NavigationCallbackHelper onStartedCallback = new NavigationCallbackHelper();
         public NavigationCallbackHelper onCommittedCallback = new NavigationCallbackHelper();
         public NavigationCallbackHelper onCompletedCallback = new NavigationCallbackHelper();
+        public CallbackHelper onFirstContentfulPaintCallback = new CallbackHelper();
 
         @Override
         public void navigationStarted(Navigation navigation) {
@@ -72,6 +73,11 @@ public class NavigationTest {
         public void navigationCompleted(Navigation navigation) {
             onCompletedCallback.notifyCalled(navigation.getUri());
         }
+
+        @Override
+        public void onFirstContentfulPaint() {
+            onFirstContentfulPaintCallback.notifyCalled();
+        }
     }
 
     private final Observer mObserver = new Observer();
@@ -85,12 +91,15 @@ public class NavigationTest {
         int curStartedCount = mObserver.onStartedCallback.getCallCount();
         int curCommittedCount = mObserver.onCommittedCallback.getCallCount();
         int curCompletedCount = mObserver.onCompletedCallback.getCallCount();
+        int curOnFirstContentfulPaintCount =
+                mObserver.onFirstContentfulPaintCallback.getCallCount();
 
         mActivityTestRule.navigateAndWait(URL2);
 
         mObserver.onStartedCallback.assertCalledWith(curStartedCount, URL2);
         mObserver.onCommittedCallback.assertCalledWith(curCommittedCount, URL2);
         mObserver.onCompletedCallback.assertCalledWith(curCompletedCount, URL2);
+        mObserver.onFirstContentfulPaintCallback.waitForCallback(curOnFirstContentfulPaintCount);
     }
 
     @Test