[Installable] InstallableManager should never return nullptr Manifest.

The new error pathway populated the manifest pointer as a nullptr. The
code can assume that this is never a nullptr, so instead just create
a dummy empty manifest on the stack and send a pointer to that.

Bug: 1110771
Change-Id: If358b4d7251b0a6a858cf91e511dda60ba02ee89
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2327277Reviewed-by: Dominick Ng <dominickn@chromium.org>
Reviewed-by: Glen Robertson <glenrob@chromium.org>
Commit-Queue: Daniel Murphy <dmurph@chromium.org>
Auto-Submit: Daniel Murphy <dmurph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795037}

chrome/browser/installable/installable_task_queue.cc

@@ -67,18 +67,20 @@ void InstallableTaskQueue::ResetWithError(InstallableStatusCode code) {
   std::deque<InstallableTask> paused_tasks = std::move(paused_tasks_);
   // Some callbacks might be already invalidated on certain resets, so we must
   // check for that.
+  // Manifest is assumed to be non-null, so we create an empty one here.
+  blink::Manifest manifest;
   for (InstallableTask& task : tasks) {
     if (task.callback) {
       std::move(task.callback)
-          .Run(InstallableData({code}, GURL(), nullptr, GURL(), nullptr, false,
-                               GURL(), nullptr, false, false));
+          .Run(InstallableData({code}, GURL(), &manifest, GURL(), nullptr,
+                               false, GURL(), nullptr, false, false));
     }
   }
   for (InstallableTask& task : paused_tasks) {
     if (task.callback) {
       std::move(task.callback)
-          .Run(InstallableData({code}, GURL(), nullptr, GURL(), nullptr, false,
-                               GURL(), nullptr, false, false));
+          .Run(InstallableData({code}, GURL(), &manifest, GURL(), nullptr,
+                               false, GURL(), nullptr, false, false));
     }
   }
 }