Add text field change handling for autofill preview in textarea element.

Source/core/html/HTMLTextAreaElement.cpp

Index: Source/core/html/HTMLTextAreaElement.cpp
diff --git a/Source/core/html/HTMLTextAreaElement.cpp b/Source/core/html/HTMLTextAreaElement.cpp
index e35f10714f33d76a99ffd5d3dd5a8a2df15f1d73..baf93e1064943227b68e5bc03dfc7202fabb7231 100644
--- a/Source/core/html/HTMLTextAreaElement.cpp
+++ b/Source/core/html/HTMLTextAreaElement.cpp
@@ -45,6 +45,9 @@
 #include "core/html/shadow/ShadowElementNames.h"
 #include "core/html/shadow/TextControlInnerElements.h"
 #include "core/frame/Frame.h"
+#include "core/frame/FrameHost.h"
+#include "core/page/Chrome.h"
+#include "core/page/ChromeClient.h"
 #include "core/rendering/RenderTextControlMultiLine.h"
 #include "platform/text/PlatformLocale.h"
 #include "wtf/StdLibExtras.h"
@@ -277,6 +280,9 @@ void HTMLTextAreaElement::subtreeHasChanged()
 
     // When typing in a textarea, childrenChanged is not called, so we need to force the directionality check.
     calculateAndAdjustDirectionality();
+
+    ASSERT(document().isActive());
+    document().frameHost()->chrome().client().didChangeValueInTextField(*this);
 }
 
 void HTMLTextAreaElement::handleBeforeTextInsertedEvent(BeforeTextInsertedEvent* event) const
@@ -436,10 +442,14 @@ String HTMLTextAreaElement::suggestedValue() const
 void HTMLTextAreaElement::setSuggestedValue(const String& value)
 {
     m_suggestedValue = value;
-    setInnerTextValue(m_suggestedValue);
-    updatePlaceholderVisibility(false);
     setNeedsStyleRecalc(SubtreeStyleChange);
-    setFormControlValueMatchesRenderer(true);
+    if (!value.isNull()) {
+        setInnerTextValue(m_suggestedValue);
+        updatePlaceholderVisibility(false);
+    } else {
+        setInnerTextValue(m_value);
+        updatePlaceholderVisibility(false);

[tkent, 2014/02/06 00:05:45]

nit: we can merge updatePlaceholderVisibility calls into one.

[ziran.sun, 2014/02/06 10:32:17]

Done.

+    }
 }
 
 String HTMLTextAreaElement::validationMessage() const