Use DownloadManager to download non-html res when download icon pressed

chrome/browser/android/offline_pages/downloads/offline_page_download_bridge.cc

 // 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.
 
 #include "chrome/browser/android/offline_pages/downloads/offline_page_download_bridge.h"
 
 #include <vector>
 
 #include "base/android/jni_string.h"
 #include "base/bind.h"
@@ skipping 10 matching lines @@
 #include "chrome/browser/android/tab_android.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_android.h"
 #include "components/offline_pages/core/background/request_coordinator.h"
 #include "components/offline_pages/core/client_namespace_constants.h"
 #include "components/offline_pages/core/client_policy_controller.h"
 #include "components/offline_pages/core/downloads/download_ui_item.h"
 #include "components/offline_pages/core/offline_page_feature.h"
 #include "components/offline_pages/core/offline_page_model.h"
 #include "content/public/browser/browser_context.h"
+#include "content/public/browser/download_manager.h"
+#include "content/public/browser/download_url_parameters.h"
+#include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/web_contents.h"
 #include "jni/OfflinePageDownloadBridge_jni.h"
 #include "net/base/filename_util.h"
 #include "url/gurl.h"
 
 using base::android::AttachCurrentThread;
 using base::android::ConvertJavaStringToUTF8;
 using base::android::ConvertUTF8ToJavaString;
 using base::android::ConvertUTF16ToJavaString;
 using base::android::JavaParamRef;
@@ skipping 289 matching lines @@
     const JavaParamRef<jobject>& j_tab) {
   TabAndroid* tab = TabAndroid::GetNativeTab(env, j_tab);
   if (!tab)
     return;
 
   content::WebContents* web_contents = tab->web_contents();
   if (!web_contents)
     return;
 
   GURL url = web_contents->GetLastCommittedURL();
+  if (url.is_empty())
+    return;
+
   GURL original_url =
       offline_pages::OfflinePageUtils::GetOriginalURLFromWebContents(
           web_contents);
 
+  // If the page is not a HTML page, route to DownloadManager.
+  if (!offline_pages::OfflinePageUtils::CanDownloadAsOfflinePage(
+          web_contents->GetContentsMimeType())) {
+    content::DownloadManager* dlm = content::BrowserContext::GetDownloadManager(
+        web_contents->GetBrowserContext());
+    std::unique_ptr<content::DownloadUrlParameters> dl_params(
+        content::DownloadUrlParameters::CreateForWebContentsMainFrame(
+            web_contents, url));
+
+    content::NavigationEntry* entry =
+        web_contents->GetController().GetLastCommittedEntry();
+    DCHECK(entry);

[Dmitry Titov, 2017/04/27 23:02:45]

I'd just do if(!entry) return here...
Otherwise it looks like a crash you sometimes expect.

[jianli, 2017/04/28 00:21:59]

GetLastCommittedURL should return an empty URL if the entry does not exist. So I
added a check at line 343. Using DCHECK here should be safe.

+    content::Referrer referrer =
+        content::Referrer::SanitizeForRequest(url, entry->GetReferrer());
+    dl_params->set_referrer(referrer);
+
+    dl_params->set_prefer_cache(true);
+    dl_params->set_prompt(false);
+    dlm->DownloadUrl(std::move(dl_params));
+    return;
+  }
+
   ScopedJavaGlobalRef<jobject> j_tab_ref(env, j_tab);
 
   OfflinePageUtils::CheckDuplicateDownloads(
       tab->GetProfile()->GetOriginalProfile(), url,
       base::Bind(&DuplicateCheckDone, url, original_url, j_tab_ref));
 }
 
 void OfflinePageDownloadBridge::CancelDownload(
     JNIEnv* env,
     const JavaParamRef<jobject>& obj,
@@ skipping 110 matching lines @@
         base::MakeUnique<DownloadUIAdapterDelegate>(offline_page_model));
     DownloadUIAdapter::AttachToOfflinePageModel(adapter, offline_page_model);
   }
 
   return reinterpret_cast<jlong>(
       new OfflinePageDownloadBridge(env, obj, adapter, browser_context));
 }
 
 }  // namespace android
 }  // namespace offline_pages