win: Fix unexpected insert after delete of composition

This CL fixes crbug/1161831 by partially reverting crrev.com/c/2580971

Issue: ResetCompositionState() sets |selection_| to client's composition
end. This is problematic when the user deletes the composition, in which
case |ResetCompositionState| is called in OnEndEdit(), before the
composition in Blink is updated.

This CL fixes the issue by restricting ResetCompositionState() to cases
initiated by the browser. i.e. remove ResetCompositionState() from
OnEndEdit().

TEST=manually verify crbug 1161831

Bug: 1161831
Change-Id: I1791e25faf737915aa5c491defa6e766f84507c0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2618292Reviewed-by: Siye Liu <siliu@microsoft.com>
Reviewed-by: Yohei Yukawa <yukawa@chromium.org>
Commit-Queue: Keren Zhu <kerenzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#841865}

ui/base/ime/win/tsf_text_store.cc

@@ -972,8 +972,15 @@ HRESULT TSFTextStore::OnEndEdit(ITfContext* context,
   }
 
   composition_start_ = selection_.start();
-  if (has_composition_range_)
-    ResetCompositionState();
+  if (has_composition_range_) {
+    has_composition_range_ = false;
+    composition_range_.set_start(0);
+    composition_range_.set_end(0);
+    previous_composition_string_.clear();
+    previous_composition_start_ = 0;
+    previous_composition_selection_range_ = gfx::Range::InvalidRange();
+    previous_text_spans_.clear();
+  }
 
   return S_OK;
 }