Fixes extensions install prompt.

The override of extensions install prompt text has regressed with
Chromium 83 update.

Removed BravePrompt that inherited from ExtensionInstallPrompt::Prompt
and overrode GetDialogTitle method. Instead, renamed the original method
to GetDialogTitle_ChromiumImpl and added our own GetDialogTitle.

Fixes brave/brave-browser#10113

The regression is due to Chromium change that was creating
ExtensionInstallPrompt::Prompt from
WebstorePrivateBeginInstallWithManifest3Function::OnWebstoreParseSuccess.

Chromium change:

https://chromium.googlesource.com/chromium/src/+/4f35260605f0a6fa5153bcc40cc9ed7b235fddec

commit 4f35260605f0a6fa5153bcc40cc9ed7b235fddec
Author: Danan S <[email protected]>
Date:   Fri Mar 27 00:41:17 2020 +0000

    Reland "Changes to Webstore Private API to support child extension installation"

    This relands the feature originally landed in
    99ffda8ef2c76aa79923281a57c82a70e68d0d45

    That CL was reverted due to an use-after-free error triggered by
    ExtensionWebstorePrivateApiTestChildInstallEnabled, but caused
    by already landed code used by the Webstore Private API.

    The actual fix for the use-after-free was fixed in http://crrev.com/c/2100548

    That fix involved changes in the ParentPermissionDialog APIs, which are
    reflected in this reland CL.

    Original change's description:
    > Revert "Changes to Webstore Private API to support child extension installation"
    >
    > This reverts commit 99ffda8ef2c76aa79923281a57c82a70e68d0d45.
    >
    > Reason for revert: browser_tests failing on https://ci.chromium.org/p/chromium/builders/ci/Linux%20Chromium%20OS%20ASan%20LSan%20Tests%20%281%29/37129 and https://ci.chromium.org/p/chromium/builders/ci/Linux%20ChromiumOS%20MSan%20Tests/18174
    >
    > Original change's description:
    > > Changes to Webstore Private API to support child extension installation
    > >
    > > These changes are required in order to prompt a child user to get
    > > parent permission when they attempt to install an extension in the
    > > Chrome Webstore.
    > >
    > > This CL also enables the feature by default.
    > >
    > > Bug: 957832

browser/extensions/BUILD.gn

@@ -33,8 +33,6 @@ source_set("extensions") {
     "brave_component_extension_resource_manager.h",
     "brave_component_loader.cc",
     "brave_component_loader.h",
-    "brave_extension_install_prompt.cc",
-    "brave_extension_install_prompt.h",
     "brave_extension_management.cc",
     "brave_extension_management.h",
     "brave_extension_provider.cc",

browser/extensions/brave_extension_install_prompt.cc → chromium_src/chrome/browser/extensions/extension_install_prompt.cc

@@ -3,21 +3,25 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "brave/browser/extensions/brave_extension_install_prompt.h"
+#include "chrome/browser/extensions/extension_install_prompt.h"
 
 #include "brave/browser/brave_browser_process_impl.h"
 #include "brave/components/brave_component_updater/browser/extension_whitelist_service.h"
 #include "brave/grit/brave_generated_resources.h"
 #include "ui/base/l10n/l10n_util.h"
 
-base::string16 BravePrompt::GetDialogTitle() const {
+#define GetDialogTitle GetDialogTitle_ChromiumImpl
+#include "../../../../../chrome/browser/extensions/extension_install_prompt.cc"
+#undef GetDialogTitle
+
+base::string16 ExtensionInstallPrompt::Prompt::GetDialogTitle() const {
   if (!g_brave_browser_process->extension_whitelist_service()->IsVetted(
-      extension())) {
+          extension())) {
     if (type_ == ExtensionInstallPrompt::INSTALL_PROMPT ||
         type_ == ExtensionInstallPrompt::WEBSTORE_WIDGET_PROMPT) {
       return l10n_util::GetStringUTF16(
           IDS_UNVETTED_EXTENSION_INSTALL_PROMPT_TITLE);
     }
   }
-  return ExtensionInstallPrompt::Prompt::GetDialogTitle();
+  return GetDialogTitle_ChromiumImpl();
 }

chromium_src/chrome/browser/extensions/extension_install_prompt.h

@@ -6,15 +6,11 @@
 #ifndef BRAVE_CHROMIUM_SRC_CHROME_BROWSER_EXTENSIONS_EXTENSION_INSTALL_PROMPT_H_
 #define BRAVE_CHROMIUM_SRC_CHROME_BROWSER_EXTENSIONS_EXTENSION_INSTALL_PROMPT_H_
 
-#define GetDialogTitle virtual GetDialogTitle
+#define GetDialogTitle    \
+  GetDialogTitle_ChromiumImpl() const; \
+  base::string16 GetDialogTitle
 
-#define BRAVE_EXTENSION_INSTALL_PROMPT_H \
- private:                                \
-  friend class BravePrompt;              \
-                                         \
- public:
 #include "../../../../../chrome/browser/extensions/extension_install_prompt.h"
-#undef BRAVE_EXTENSION_INSTALL_PROMPT_H_
 #undef GetDialogTitle
 
 #endif  // BRAVE_CHROMIUM_SRC_CHROME_BROWSER_EXTENSIONS_EXTENSION_INSTALL_PROMPT_H_