Adds selection expansion support for Contextual Search.

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index b194b1d6f1ce06fdbf6098b3ac3bb8d4f59ebff6..71f4d749df0dc3f2d2ca234b0aa315053970f1cf 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -1354,6 +1354,8 @@ bool RenderViewImpl::OnMessageReceived(const IPC::Message& message) {
                         OnReleaseDisambiguationPopupBitmap)
     IPC_MESSAGE_HANDLER(ViewMsg_ForceRedraw, OnForceRedraw)
     IPC_MESSAGE_HANDLER(ViewMsg_SelectWordAroundCaret, OnSelectWordAroundCaret)
+    IPC_MESSAGE_HANDLER(ViewMsg_MoveSelectionByCharacterOffset,
+                        OnMoveSelectionByCharacterOffset)
 #if defined(OS_ANDROID)
     IPC_MESSAGE_HANDLER(InputMsg_ActivateNearestFindResult,
                         OnActivateNearestFindResult)
@@ -1390,6 +1392,25 @@ void RenderViewImpl::OnSelectWordAroundCaret() {
   handling_input_event_ = false;
 }
 
+void RenderViewImpl::OnMoveSelectionByCharacterOffset(int start_adjust,
+                                                      int end_adjust) {
+  if (!webview())
+    return;
+
+  handling_input_event_ = true;
+  size_t start, length;
+  if (webview()->caretOrSelectionRange(&start, &length)) {
+    start += start_adjust;
+    length += end_adjust - start_adjust;

[David Trainor- moved to gerrit, 2015/06/25 00:34:55]

Do some checks on this stuff to make sure these values are valid after the
adjustments.  size_t is unsigned right?

+    WebLocalFrame* web_local_frame =
+        webview()->focusedFrame()->toWebLocalFrame();
+    web_local_frame->selectRange(WebRange::fromDocumentRange(web_local_frame,
+                                                             start,
+                                                             length));
+  }
+  handling_input_event_ = false;
+}
+
 void RenderViewImpl::OnCopyImageAt(int x, int y) {
   webview()->copyImageAt(WebPoint(x, y));
 }