[Android WebView] Implement the capture picture API.

android_webview/common/render_view_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 "android_webview/common/aw_hit_test_data.h"
 #include "content/public/common/common_param_traits.h"
 #include "ipc/ipc_channel_handle.h"
 #include "ipc/ipc_message_macros.h"
 #include "ipc/ipc_platform_file.h"
@@ skipping 37 matching lines @@
 // physical pixel values with the 0,0 at the top left of the current displayed
 // view (ie 0,0 is not the top left of the page if the page is scrolled).
 IPC_MESSAGE_ROUTED2(AwViewMsg_DoHitTest,
                     int /* view_x */,
                     int /* view_y */)
 
 // Enables receiving pictures from the renderer on every new frame.
 IPC_MESSAGE_ROUTED1(AwViewMsg_EnableCapturePictureCallback,
                     bool /* enable */)
 
+// Requests a new picture with the latest renderer contents synchronously.
+// This message blocks the browser process on the renderer until complete.
+IPC_SYNC_MESSAGE_ROUTED0_0(AwViewMsg_CapturePictureSync)
+
 //-----------------------------------------------------------------------------
 // RenderView messages
 // These are messages sent from the renderer to the browser process.
 
 // Response to AwViewMsg_DocumentHasImages request.
 IPC_MESSAGE_ROUTED2(AwViewHostMsg_DocumentHasImagesResponse,
                     int, /* id */
                     bool /* has_images */)
 
 // Response to AwViewMsg_DoHitTest.
 IPC_MESSAGE_ROUTED1(AwViewHostMsg_UpdateHitTestData,
                     android_webview::AwHitTestData)
 
 // Notification that a new picture becomes available. It is only sent if
 // AwViewMsg_EnableCapturePictureCallback was previously enabled.
 IPC_MESSAGE_ROUTED0(AwViewHostMsg_PictureUpdated)