Introduce ManifestUpgradeDetector for WebAPK to detect web manifest changes.

chrome/browser/android/webapk/manifest_upgrade_detector.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_ANDROID_WEBAPK_MANIFEST_UPGRADE_DETECTOR_H_
+#define CHROME_BROWSER_ANDROID_WEBAPK_MANIFEST_UPGRADE_DETECTOR_H_
+
+#include "base/android/jni_android.h"
+#include "base/android/jni_weak_ref.h"
+#include "base/gtest_prod_util.h"
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "content/public/browser/web_contents_observer.h"
+
+namespace content {
+struct Manifest;
+class WebContents;
+}
+
+class GURL;
+struct ShortcutInfo;
+
+// ManifestUpgradeDetector is the C++ counterpart of
+// org.chromium.chrome.browser's ManifestUpgradeDetector in Java. It is created
+// via a JNI (Initialize) call and MUST BE DESTROYED via Destroy().
+class ManifestUpgradeDetector : public content::WebContentsObserver {
+ public:
+  enum ErrorCode {
+    NoErrorDetected,
+    FetchedManifestEmpty,
+  };
+
+  ManifestUpgradeDetector(JNIEnv* env,
+                          jobject obj,
+                          content::WebContents* web_contents,
+                          const GURL& scope,
+                          const GURL& web_manifest_url);
+
+  // Replaces the WebContents that is being observed.
+  void ReplaceWebContents(
+      JNIEnv* env,
+      const base::android::JavaParamRef<jobject>& obj,
+      const base::android::JavaParamRef<jobject>& jweb_contents);
+
+  // Called by the Java counterpart to destroy its native half.
+  void Destroy(JNIEnv* env, const base::android::JavaParamRef<jobject>& obj);
+
+  // Called by the Java counterpart to start checking web manifest changes.
+  void Start(JNIEnv* env, const base::android::JavaParamRef<jobject>& obj);
+
+  // Registers JNI hooks.
+  static bool Register(JNIEnv* env);
+
+  ErrorCode error_code() { return error_code_; }
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(ManifestUpgradeDetectorTest,
+              OnDidGetManifestReturnsFalseWhenTheFetchedManifestUrlIsEmpty);
+  ~ManifestUpgradeDetector() override;
+
+  // content::WebContentsObserver:
+  void DidFinishLoad(content::RenderFrameHost* render_frame_host,
+                     const GURL& validated_url) override;
+
+  // Called when the Manifest has been parsed, or if no Manifest was found.
+  void OnDidGetManifest(const GURL& manifest_url,
+                        const content::Manifest& manifest);
+
+  void OnDataAvailable(const ShortcutInfo& info);
+
+  // Points to the Java object.
+  base::android::ScopedJavaGlobalRef<jobject> java_ref_;
+
+  // A flag to indicate if the detection pipeline was started.
+  bool started_;
+
+  // The detector will only fetch the URL within the scope of the WebAPK.
+  const GURL scope_;
+
+  // The WebAPK's Web Manifest URL that the detector is looking for.
+  const GURL web_manifest_url_;
+
+  // Error message code.
+  ErrorCode error_code_;
+
+  base::WeakPtrFactory<ManifestUpgradeDetector> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ManifestUpgradeDetector);
+};
+
+#endif  // CHROME_BROWSER_ANDROID_WEBAPK_MANIFEST_UPGRADE_DETECTOR_H_