Initial CL for talking to the WebAPK server to generate WebAPK

chrome/browser/android/webapps/add_to_homescreen_dialog_helper.cc

 // Copyright 2015 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/webapps/add_to_homescreen_dialog_helper.h"
 
 #include <jni.h>
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
@@ skipping 26 matching lines @@
 AddToHomescreenDialogHelper::AddToHomescreenDialogHelper(
     JNIEnv* env,
     jobject obj,
     content::WebContents* web_contents)
     : add_shortcut_pending_(false),
       data_fetcher_(new AddToHomescreenDataFetcher(web_contents,
           ShortcutHelper::GetIdealHomescreenIconSizeInDp(),
           ShortcutHelper::GetMinimumHomescreenIconSizeInDp(),
           ShortcutHelper::GetIdealSplashImageSizeInDp(),
           ShortcutHelper::GetMinimumSplashImageSizeInDp(),
-          this)) {
+          this)),
+      browser_context_(web_contents->GetBrowserContext()) {

[dominickn, 2016/08/02 04:24:24]

Instead of adding this extra member, can you just call
data_fetcher_->web_contents()->GetBrowserContext() in AddShortcut?

[pkotwicz, 2016/08/02 20:49:29]

It is possible for the tab that a user requested be added to the homescreen to
be closed prior to the user selecting "ADD" in the "Add to Home screen" dialog.
I have a test page which closes itself at https://jsfiddle.net/nbq637k8/5/

This means that calling data_fetcher_->web_contents()->GetBrowserContext() in
AddToHomescreenDialogHelper#AddShortcut() may cause a Segfault. I am unsure what
the correct solution is. Should we not create a shortcut in this scenario? (And
display some error message?)

[dominickn, 2016/08/02 23:41:58]

If a tab is closed before add to homescreen finishes, I think the appropriate
thing to do is to abort the procedure without an error message. That's what app
banners do if the WebContents unexpectedly closes during the pipeline. The tab
closing should take everything that's attached to it away - e.g. the add to
homescreen dialog.

Concretely, I think that just means null-checking data_fetcher_->web_contents()
in AddToHomescreenDialogHelper#AddShortcut(), and just returning if it's null.
Otherwise, pass GetBrowserContext() to ShortcutHelper. WDYT?

[pkotwicz, 2016/08/03 01:25:31]

I have added the early exit to AddToHomescreenDialogHelper#AddShortcut()

Currently, the "Add to homescreen" dialog does not close when the tab is closed
but I don't think that it is worth fixing

   java_ref_.Reset(env, obj);
 }
 
 AddToHomescreenDialogHelper::~AddToHomescreenDialogHelper() {
   data_fetcher_->set_weak_observer(nullptr);
   data_fetcher_ = nullptr;
 }
 
 void AddToHomescreenDialogHelper::OnUserTitleAvailable(
     const base::string16& user_title) {
@@ skipping 57 matching lines @@
   DCHECK(add_shortcut_pending_);
   if (!add_shortcut_pending_)
     return;
   add_shortcut_pending_ = false;
 
   RecordAddToHomescreen();
 
   const std::string& uid = base::GenerateGUID();
   content::BrowserThread::PostTask(
       content::BrowserThread::IO, FROM_HERE,
-      base::Bind(&ShortcutHelper::AddToLauncherInBackgroundWithSkBitmap, info,
-                 uid, icon,
+      base::Bind(&ShortcutHelper::AddToLauncherInBackgroundWithSkBitmap,
+                 browser_context_, info, uid, icon,
                  data_fetcher_->FetchSplashScreenImageCallback(uid)));
 }
 
 bool AddToHomescreenDialogHelper::RegisterAddToHomescreenDialogHelper(
       JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 void AddToHomescreenDialogHelper::RecordAddToHomescreen() {
   // Record that the shortcut has been added, so no banners will be shown
   // for this app.
   content::WebContents* web_contents = data_fetcher_->web_contents();
   if (!web_contents)
     return;
 
   AppBannerSettingsHelper::RecordBannerEvent(
       web_contents, web_contents->GetURL(),
       data_fetcher_->shortcut_info().url.spec(),
       AppBannerSettingsHelper::APP_BANNER_EVENT_DID_ADD_TO_HOMESCREEN,
       base::Time::Now());
 }