Introduce the abstract class WebViewBase, to decouple WebViewImpl.

third_party/WebKit/Source/web/StorageClientImpl.cpp

Index: third_party/WebKit/Source/web/StorageClientImpl.cpp
diff --git a/third_party/WebKit/Source/web/StorageClientImpl.cpp b/third_party/WebKit/Source/web/StorageClientImpl.cpp
index 1aa13d075b44227c3db50341320b91eb63f224a2..3b9df8179bbc16bb4fb3bc9652b5542826310bf7 100644
--- a/third_party/WebKit/Source/web/StorageClientImpl.cpp
+++ b/third_party/WebKit/Source/web/StorageClientImpl.cpp
@@ -26,12 +26,12 @@
 #include "web/StorageClientImpl.h"
 
 #include <memory>
+#include "core/exported/WebViewBase.h"
 #include "core/frame/ContentSettingsClient.h"
 #include "modules/storage/StorageNamespace.h"
 #include "platform/wtf/PtrUtil.h"
 #include "public/platform/WebStorageNamespace.h"
 #include "public/web/WebViewClient.h"
-#include "web/WebViewImpl.h"
 
 namespace blink {
 
@@ -43,7 +43,7 @@ STATIC_ASSERT_MATCHING_ENUM(kLocalStorage,
 STATIC_ASSERT_MATCHING_ENUM(kSessionStorage,
                             ContentSettingsClient::StorageType::kSession);
 
-StorageClientImpl::StorageClientImpl(WebViewImpl* web_view)
+StorageClientImpl::StorageClientImpl(WebViewBase* web_view)
     : web_view_(web_view) {}
 
 std::unique_ptr<StorageNamespace>