Add a DCHECK to prevent a future issue with 3p blocking

The ModuleBlacklistCacheUpdater currently doesn't support a module first
loading into a process where injection is allowed then loading into one
where it should be blocked.

This DCHECK ensures this limitation will be addressed before adding
another supported process type.

Bug: 662084
Change-Id: Id49f323ee2e9a53bdafcd8f7391495e26d5d8cce
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1879948
Auto-Submit: Patrick Monette <pmonette@chromium.org>
Commit-Queue: Chris Hamilton <chrisha@chromium.org>
Reviewed-by: Chris Hamilton <chrisha@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710987}

chrome/browser/win/conflicts/module_database.cc

@@ -219,6 +219,11 @@ void ModuleDatabase::OnModuleLoad(content::ProcessType process_type,
                                   uint32_t module_time_date_stamp) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
 
+  DCHECK(process_type == content::PROCESS_TYPE_BROWSER ||
+         process_type == content::PROCESS_TYPE_RENDERER)
+      << "The current logic in ModuleBlacklistCacheUpdater does not support "
+         "other process types yet. See https://crbug.com/662084 for details.";
+
   ModuleInfo* module_info = nullptr;
   bool new_module = FindOrCreateModuleInfo(
       module_path, module_size, module_time_date_stamp, &module_info);

chrome/browser/win/conflicts/module_database_observer.h

@@ -10,9 +10,11 @@ struct ModuleInfoData;
 
 class ModuleDatabaseObserver {
  public:
-  // Invoked when a new module is found either by loading into the process, or
-  // by being registered as a shell extension or IME. Only invoked after the
+  // Invoked when a new module is found either by loading into a Chrome process,
+  // or by being registered as a shell extension or IME. Only invoked after the
   // module was inspected on disk.
+  // Note that this is not invoked multiple times if the module subsequently
+  // loads into a different process type.
   virtual void OnNewModuleFound(const ModuleInfoKey& module_key,
                                 const ModuleInfoData& module_data) {}