Revert "[Smart Text] Disable surrounding text for input elements."

This reverts commit afd38807.

Reason for revert: breaks smart text selection for GMail editor, http://crbug.com/757945

Original change's description:
> [Smart Text] Disable surrounding text for input elements.
> 
> This CL effectively reverts
> https://codereview.chromium.org/2907963002, which appears to
> causing problems, including leaking of input fields to
> Google servers.
> 
> Disabling until a better fix is found.
> 
> BUG=751408, 753579, 721840
> 
> Change-Id: Iecddba6ebed8faf3c266daa232613c57fa5a7464
> Reviewed-on: https://chromium-review.googlesource.com/622747
> Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
> Commit-Queue: Tima Vaisburd <timav@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#495985}

TBR=yosin@chromium.org,donnd@chromium.org,timav@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 751408, 753579, 721840
Change-Id: Ifc8d987a25fe1b98a206dbd6e572436444545490
Reviewed-on: https://chromium-review.googlesource.com/627576Reviewed-by: Tima Vaisburd <timav@chromium.org>
Reviewed-by: Donn Denman <donnd@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#496615}

third_party/WebKit/Source/core/editing/SurroundingText.cpp

@@ -64,11 +64,14 @@ void SurroundingText::Initialize(const Position& start_position,
     return;
   DCHECK(!document->NeedsLayoutTreeUpdate());
 
-  // Do not create surrounding text for input elements.
+  // The forward range starts at the selection end and ends at the document's
+  // or the input element's end. It will then be updated to only contain the
+  // text in the right range around the selection.
   DCHECK_EQ(RootEditableElementOf(start_position),
             RootEditableElementOf(end_position));
-  if (RootEditableElementOf(start_position))
-    return;
+  Element* const root_editable = RootEditableElementOf(start_position);
+  Element* const root_element =
+      root_editable ? root_editable : document->documentElement();
 
   // Do not create surrounding text if start or end position is within a
   // control.
@@ -78,13 +81,9 @@ void SurroundingText::Initialize(const Position& start_position,
           end_position.ComputeContainerNode()))
     return;
 
-  // The forward range starts at the selection end and ends at the document's
-  // end. It will then be updated to only contain the text in the right range
-  // around the selection.
   CharacterIterator forward_iterator(
       end_position,
-      Position::LastPositionInNode(*document->documentElement())
-          .ParentAnchoredEquivalent(),
+      Position::LastPositionInNode(*root_element).ParentAnchoredEquivalent(),
       TextIteratorBehavior::Builder().SetStopsOnFormControls(true).Build());
   if (!forward_iterator.AtEnd())
     forward_iterator.Advance(max_length - half_max_length);
@@ -93,8 +92,7 @@ void SurroundingText::Initialize(const Position& start_position,
   // starts at the document's or input element's start and ends at the selection
   // start and will be updated.
   BackwardsCharacterIterator backwards_iterator(
-      Position::FirstPositionInNode(*document->documentElement())
-          .ParentAnchoredEquivalent(),
+      Position::FirstPositionInNode(*root_element).ParentAnchoredEquivalent(),
       start_position,
       TextIteratorBehavior::Builder().SetStopsOnFormControls(true).Build());
   if (!backwards_iterator.AtEnd())

third_party/WebKit/Source/core/editing/SurroundingTextTest.cpp

@@ -11,6 +11,7 @@
 #include "core/editing/Position.h"
 #include "core/editing/VisibleSelection.h"
 #include "core/html/HTMLElement.h"
+#include "core/html/TextControlElement.h"
 #include "core/testing/DummyPageHolder.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -285,4 +286,24 @@ TEST_F(SurroundingTextTest, TreeRangeSelection) {
   }
 }
 
+TEST_F(SurroundingTextTest, TextAreaSelection) {
+  SetHTML(
+      String("<p>First paragraph</p>"
+             "<textarea id='selection'>abc def ghi</textarea>"
+             "<p>Second paragraph</p>"));
+
+  TextControlElement* text_ctrl =
+      (TextControlElement*)GetDocument().getElementById("selection");
+
+  text_ctrl->SetSelectionRange(4, 7);
+  VisibleSelection selection = CreateVisibleSelection(text_ctrl->Selection());
+
+  SurroundingText surrounding_text(
+      *CreateRange(FirstEphemeralRangeOf(selection)), 20);
+
+  EXPECT_EQ("abc def ghi", surrounding_text.Content().SimplifyWhiteSpace());
+  EXPECT_EQ(4u, surrounding_text.StartOffsetInContent());
+  EXPECT_EQ(7u, surrounding_text.EndOffsetInContent());
+}
+
 }  // namespace blink