[iOS] Allow empty aggregate Overlay[Request/Response]Support.

This allows for a more flexible API that doesn't need additional
checks to verify that conditions are met before creating supports with
their aggregate constructors.

Bug: none
Change-Id: I8e7fdf65780c698339554e5e2c7f3b0799a3a5ac
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1992004
Commit-Queue: Kurt Horimoto <kkhorimoto@chromium.org>
Auto-Submit: Kurt Horimoto <kkhorimoto@chromium.org>
Reviewed-by: Mike Dougherty <michaeldo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#729791}

ios/chrome/browser/overlays/overlay_request_support.cc

@@ -26,18 +26,13 @@ class DisabledOverlayRequestSupport : public OverlayRequestSupport {
 
 OverlayRequestSupport::OverlayRequestSupport(
     const std::vector<const OverlayRequestSupport*>& supports)
-    : aggregated_support_(supports) {
-  DCHECK(aggregated_support_.size());
-}
+    : aggregated_support_(supports) {}
 
 OverlayRequestSupport::OverlayRequestSupport() = default;
 
 OverlayRequestSupport::~OverlayRequestSupport() = default;
 
 bool OverlayRequestSupport::IsRequestSupported(OverlayRequest* request) const {
-  DCHECK(aggregated_support_.size())
-      << "Default implementation is only for aggregated support.  Subclasses "
-         "using the default constructor must implement IsRequestSupported().";
   for (const OverlayRequestSupport* support : aggregated_support_) {
     if (support->IsRequestSupported(request))
       return true;

ios/chrome/browser/overlays/overlay_response_support.cc

@@ -26,9 +26,7 @@ class DisabledOverlayResponseSupport : public OverlayResponseSupport {
 
 OverlayResponseSupport::OverlayResponseSupport(
     const std::vector<const OverlayResponseSupport*>& supports)
-    : aggregated_support_(supports) {
-  DCHECK(aggregated_support_.size());
-}
+    : aggregated_support_(supports) {}
 
 OverlayResponseSupport::OverlayResponseSupport() = default;
 
@@ -36,9 +34,6 @@ OverlayResponseSupport::~OverlayResponseSupport() = default;
 
 bool OverlayResponseSupport::IsResponseSupported(
     OverlayResponse* response) const {
-  DCHECK(aggregated_support_.size())
-      << "Default implementation is only for aggregated support.  Subclasses "
-         "using the default constructor must implement IsResponseSupported().";
   for (const OverlayResponseSupport* support : aggregated_support_) {
     if (support->IsResponseSupported(response))
       return true;

ios/chrome/browser/overlays/public/overlay_request_support.h

@@ -14,17 +14,18 @@
 class OverlayRequestSupport {
  public:
   // Creates an OverlayResponseSupport that aggregates the request support from
-  // the OverlayRequestSupports in |supports|.  |supports| must be non-empty.
-  // Instances created with this constructor will return true from
-  // IsRequestSupported() if any of the OverlayRequestSupports in |supports|
-  // returns true from IsRequestSupport() for the same request.
+  // the OverlayRequestSupports in |supports|.  Instances created with this
+  // constructor will return true from IsRequestSupported() if any of the
+  // OverlayRequestSupports in |supports| returns true from IsRequestSupport()
+  // for the same request.
   OverlayRequestSupport(
       const std::vector<const OverlayRequestSupport*>& supports);
   virtual ~OverlayRequestSupport();
 
   // Whether |request| is supported by this instance.  The default
   // implementation returns true is any OverlayRequestSupport in
-  // |aggregated_support_| returns true.
+  // |aggregated_support_| returns true, or false if |aggregated_support_| is
+  // empty.
   virtual bool IsRequestSupported(OverlayRequest* request) const;
 
   // Returns an OverlayRequestSupport that supports all requests.

ios/chrome/browser/overlays/public/overlay_response_support.h

@@ -14,15 +14,18 @@
 class OverlayResponseSupport {
  public:
   // Creates an OverlayResponseSupport that aggregates the support from
-  // the OverlayRequestSupports in |supports|.  |supports| must be non-empty.
-  // Instances created with this constructor will return true from
-  // IsResponseSupported() if any of the OverlayRequestSupports in |supports|
-  // returns true from IsResponseSupported() for the same response.
+  // the OverlayRequestSupports in |supports|.  Instances created with this
+  // constructor will return true from IsResponseSupported() if any of the
+  // OverlayRequestSupports in |supports| returns true from
+  // IsResponseSupported() for the same response.
   OverlayResponseSupport(
       const std::vector<const OverlayResponseSupport*>& supports);
   virtual ~OverlayResponseSupport();
 
-  // Whether |response| is supported by this instance.
+  // Whether |response| is supported by this instance.  The default
+  // implementation returns true is any OverlayResponseSupport in
+  // |aggregated_support_| returns true, or false if |aggregated_support_| is
+  // empty.
   virtual bool IsResponseSupported(OverlayResponse* response) const;
 
   // Returns an OverlayResponseSupport that supports all responses.