components/translate/content/browser/browser_cld_data_provider.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef COMPONENTS_TRANSLATE_CONTENT_BROWSER_BROWSER_CLD_DATA_PROVIDER_H_
   6 #define COMPONENTS_TRANSLATE_CONTENT_BROWSER_BROWSER_CLD_DATA_PROVIDER_H_
   7
   8 #include <string>
   9
  10 #include "base/compiler_specific.h"
  11 #include "base/macros.h"
  12 #include "ipc/ipc_listener.h"
  13
  14 namespace IPC {
  15 class Message;
  16 }
  17
  18 namespace translate {
  19
  20 // Browser-side interface responsible for providing CLD data.
  21 // The implementation must be paired with a renderer-side implementation of
  22 // the RendererCldDataProvider class:
  23 //   ../renderer/renderer_cld_data_provider.h
  24 //
  25 // The glue between them is typically a pair of request/response IPC messages
  26 // using the "CldDataProviderMsgStart" IPCMessageStart enumerated constant from
  27 // ipc_message_start.h
  28 //
  29 // In general, instances of this class should be obtained by using the
  30 // BrowserCldDataProviderFactory::CreateBrowserCldProvider(...). For more
  31 // information, see browser_cld_data_provider_factory.h.
  32 class BrowserCldDataProvider : public IPC::Listener {
  33  public:
  34   BrowserCldDataProvider() {}
  35   ~BrowserCldDataProvider() override {}
  36
  37   // IPC::Listener implementation:
  38   // If the specified message is a request for CLD data, invokes
  39   // OnCldDataRequest() and returns true. In all other cases, this method does
  40   // nothing. This method is defined as virtual in order to force the
  41   // implementation to define the specific IPC message(s) that it handles.
  42   // The default implementation does nothing and returns false.
  43   bool OnMessageReceived(const IPC::Message&) override;
  44
  45   // Called when the browser process receives an appropriate message in
  46   // OnMessageReceived, above. The implementation should attempt to locate
  47   // the CLD data, cache any metadata required for accessing that data, and
  48   // ultimately trigger a response by invoking SendCldDataResponse.
  49   // The renderer process may poll for data, in which case this method may be
  50   // repeatedly invoked. The implementation must be safe to call any number
  51   // of times.
  52   // The default implementation does nothing.
  53   virtual void OnCldDataRequest() {}
  54
  55   // Invoked when OnCldDataRequest, above, results in a successful lookup or
  56   // the data is already cached and ready to respond to. The implementation
  57   // should take whatever action is appropriate for responding to the paired
  58   // RendererCldDataProvider, typically by sending an IPC response.
  59   // The default implementation does nothing.
  60   virtual void SendCldDataResponse() {}
  61
  62  private:
  63   DISALLOW_COPY_AND_ASSIGN(BrowserCldDataProvider);
  64 };
  65
  66 }  // namespace translate
  67
  68 #endif  // COMPONENTS_TRANSLATE_CONTENT_BROWSER_BROWSER_CLD_DATA_PROVIDER_H_