Return nullptr from GetRenderer() when the map doesn't have the process

Previously RendererStartupHelper::GetRenderer() returns
mojom::Renderer* having DCHECK that makes sure the map includes
it. But, GetRenderer() would be accessed before the map is updated.

This CL returns nullptr from RendererStartupHelper::GetRenderer()
when |process_mojo_map_| doesn't have the information corresponding
to the process.

Bug: 1157200
Change-Id: Ifacc4cfcd9457716d7eca700b7df4be8576f68b9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2583663
Commit-Queue: Julie Kim <jkim@igalia.com>
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836393}

chrome/browser/extensions/activity_log/activity_log.cc

@@ -794,6 +794,7 @@ void ActivityLog::CheckActive(bool use_cached) {
           RendererStartupHelperFactory::GetForBrowserContext(
               host->GetBrowserContext())
               ->GetRenderer(host);
+      if (renderer)
         renderer->SetActivityLoggingEnabled(is_active_);
     }
   }

extensions/browser/renderer_startup_helper.cc

@@ -289,8 +289,9 @@ void RendererStartupHelper::OnExtensionUnloaded(const Extension& extension) {
   const std::set<content::RenderProcessHost*>& loaded_process_set =
       extension_process_map_[extension.id()];
   for (content::RenderProcessHost* process : loaded_process_set) {
-    DCHECK(base::Contains(process_mojo_map_, process));
-    GetRenderer(process)->UnloadExtension(extension.id());
+    mojom::Renderer* renderer = GetRenderer(process);
+    if (renderer)
+      renderer->UnloadExtension(extension.id());
   }
 
   // Resets registered origin access lists in the BrowserContext asynchronously.
@@ -317,7 +318,8 @@ RendererStartupHelper::BindNewRendererRemote(
 
 mojom::Renderer* RendererStartupHelper::GetRenderer(
     content::RenderProcessHost* process) {
-  DCHECK(base::Contains(process_mojo_map_, process));
+  if (!base::Contains(process_mojo_map_, process))
+    return nullptr;
   return process_mojo_map_.find(process)->second.get();
 }
 //////////////////////////////////////////////////////////////////////////////

extensions/browser/renderer_startup_helper.h

@@ -68,8 +68,10 @@ class RendererStartupHelper : public KeyedService,
   void OnExtensionUnloaded(const Extension& extension);
   void OnExtensionLoaded(const Extension& extension);
 
-  // Returns mojom::Renderer* corresponding to |process|. Note that the callers
-  // should pass a valid content::RenderProcessHost*.
+  // Returns mojom::Renderer* corresponding to |process|. This would return
+  // nullptr when it's called before |process| is inserted to
+  // |process_mojo_map_| or after it's deleted. Note that the callers should
+  // pass a valid content::RenderProcessHost*.
   mojom::Renderer* GetRenderer(content::RenderProcessHost* process);
 
  protected: