Image Search: Move thumbnail JPEG encoding to the renderer.

chrome/common/render_messages.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Multiply-included file, no traditional include guard.
 #include <stdint.h>
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 319 matching lines @@
 IPC_MESSAGE_ROUTED3(ChromeViewMsg_UpdateTopControlsState,
                     content::TopControlsState /* constraints */,
                     content::TopControlsState /* current */,
                     bool /* animate */)
 
 
 // Updates the window features of the render view.
 IPC_MESSAGE_ROUTED1(ChromeViewMsg_SetWindowFeatures,
                     blink::WebWindowFeatures /* window_features */)
 
+// Responds to the request for a thumbnail.
+// Thumbnail data will be empty is a thumbnail could not be produced.
 IPC_MESSAGE_ROUTED2(ChromeViewHostMsg_RequestThumbnailForContextNode_ACK,
-                    SkBitmap /* thumbnail */,
+                    std::string /* JPEG-encoded thumbnail data */,
                     gfx::Size /* original size of the image */)
 
 // Requests application info for the page. The renderer responds back with
 // ChromeViewHostMsg_DidGetWebApplicationInfo.
 IPC_MESSAGE_ROUTED0(ChromeViewMsg_GetWebApplicationInfo)
 
 #if defined(OS_ANDROID)
 // Asks the renderer to return information about the given meta tag.
 IPC_MESSAGE_ROUTED2(ChromeViewMsg_RetrieveMetaTagContent,
                     GURL /* expected_url */,
@@ skipping 311 matching lines @@
 // process so that they can be assigned to an Instant renderer.
 IPC_MESSAGE_CONTROL2(ChromeViewMsg_SetSearchURLs,
                      std::vector<GURL> /* search_urls */,
                      GURL /* new_tab_page_url */)
 
 #if defined(ENABLE_PLUGINS)
 // Sent by the renderer to check if crash reporting is enabled.
 IPC_SYNC_MESSAGE_CONTROL0_1(ChromeViewHostMsg_IsCrashReportingEnabled,
                             bool /* enabled */)
 #endif