Merge 120219 - [Chromium] WebFrameImpl::find doesn't work for searching from a selection.

Source/WebKit/chromium/src/WebFrameImpl.cpp

Index: Source/WebKit/chromium/src/WebFrameImpl.cpp
===================================================================
--- Source/WebKit/chromium/src/WebFrameImpl.cpp	(revision 120226)
+++ Source/WebKit/chromium/src/WebFrameImpl.cpp	(working copy)
@@ -1566,12 +1566,14 @@
 {
     WebFrameImpl* mainFrameImpl = viewImpl()->mainFrameImpl();
 
-    if (!options.findNext) {
+    if (!options.findNext)
         frame()->page()->unmarkAllTextMatches();
-        m_activeMatch = 0;
-    } else
+    else
         setMarkerActive(m_activeMatch.get(), false);
 
+    if (m_activeMatch && m_activeMatch->ownerDocument() != frame()->document())
+        m_activeMatch = 0;
+
     // If the user has selected something since the last Find operation we want
     // to start from there. Otherwise, we start searching from where the last Find
     // operation left off (either a Find or a FindNext operation).
@@ -2185,6 +2187,14 @@
         // a link focused, which is weird).
         frame()->selection()->setSelection(m_activeMatch.get());
         frame()->document()->setFocusedNode(0);
+
+        // Finally clear the active match, for two reasons:
+        // We just finished the find 'session' and we don't want future (potentially
+        // unrelated) find 'sessions' operations to start at the same place.
+        // The WebFrameImpl could get reused and the m_activeMatch could end up pointing
+        // to a document that is no longer valid. Keeping an invalid reference around
+        // is just asking for trouble.
+        m_activeMatch = 0;
     }
 }