[Extensions] Remove the webstore API feature

The chrome.webstore API is used (exclusively) for inline install, which
is deprecated and to be removed in M71. [1] Remove the webstore entry
from the extensions features files; this will result in chrome.webstore
being undefined for all JS contexts.

[1] https://blog.chromium.org/2018/06/improving-extension-transparency-for.html

Bug: 895868

Change-Id: Idce382e5dd967a22ba779204d63e1ec509493ff4
Reviewed-on: https://chromium-review.googlesource.com/c/1283485Reviewed-by: Karan Bhatia <karandeepb@chromium.org>
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600906}

chrome/common/extensions/api/_api_features.json

@@ -784,18 +784,6 @@
       "81986D4F846CEDDDB962643FA501D1780DD441BB"   // http://crbug.com/775961
     ]
   },
-  "webstore": {
-    // Hosted apps can use the webstore API from within a blessed context.
-    "channel": "stable",
-    // Set extension_types to 'all' to prevent webstore from being filtered.
-    // Technically, webstore is not in apps or extensions, but it is currently
-    // displayed on /extensions/webstore and /apps/webstore. The "contexts"
-    // restriction effectively restricts this to hosted apps and webpages.
-    "extension_types": "all",
-    "contexts": ["blessed_web_page", "web_page"],
-    // Any webpage can use the webstore API.
-    "matches": ["<all_urls>"]
-  },
   "webstorePrivate": {
     "dependencies": ["permission:webstorePrivate"],
     // NOTE: even though this is only used by the webstore hosted app, which

extensions/renderer/extension_bindings_system.cc

@@ -33,7 +33,7 @@ bool ExtensionBindingsSystem::IsRuntimeAvailableToContext(
 
 // static
 const char* const ExtensionBindingsSystem::kWebAvailableFeatures[] = {
-    "app", "webstore", "dashboardPrivate",
+    "app", "dashboardPrivate",
 };
 
 void ExtensionBindingsSystem::LogUpdateBindingsForContextTime(

extensions/renderer/extension_bindings_system.h

@@ -93,7 +93,7 @@ class ExtensionBindingsSystem {
   // Note: `runtime` is not included here, since it's handled specially above.
   // Note: We specify the size of the array to allow for its use in for loops
   // without needing to expose a separate "kNumWebAvailableFeatures".
-  static const char* const kWebAvailableFeatures[3];
+  static const char* const kWebAvailableFeatures[2];
 };
 
 }  // namespace extensions