Initial CL for talking to the WebAPK server to generate WebAPK

chrome/browser/android/webapps/add_to_homescreen_dialog_helper.cc

Index: chrome/browser/android/webapps/add_to_homescreen_dialog_helper.cc
diff --git a/chrome/browser/android/webapps/add_to_homescreen_dialog_helper.cc b/chrome/browser/android/webapps/add_to_homescreen_dialog_helper.cc
index ba6732f42240274e61db5447ba35c5c9549c86bc..fb6d01471e36d99d16e57035d6d24c8c24fe6e60 100644
--- a/chrome/browser/android/webapps/add_to_homescreen_dialog_helper.cc
+++ b/chrome/browser/android/webapps/add_to_homescreen_dialog_helper.cc
@@ -44,7 +44,8 @@ AddToHomescreenDialogHelper::AddToHomescreenDialogHelper(
           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);
 }
 
@@ -122,8 +123,8 @@ void AddToHomescreenDialogHelper::AddShortcut(const ShortcutInfo& info,
   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)));
 }