Coverity: Fix pass by value error in IMEInputEvent_Dev.

ppapi/cpp/dev/ime_input_event_dev.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PPAPI_CPP_DEV_IME_INPUT_EVENT_DEV_H_
 #define PPAPI_CPP_DEV_IME_INPUT_EVENT_DEV_H_
 
 #include <utility>
 #include <vector>
 
@@ skipping 35 matching lines @@
   /// @param[in] segment_offsets The array of numbers returned by
   /// <code>GetSegmentOffset</code>.
   ///
   /// @param[in] target_segment The number returned by
   /// <code>GetTargetSegment</code>.
   ///
   /// @param[in] selection The range returned by <code>GetSelection</code>.
   IMEInputEvent_Dev(const InstanceHandle& instance,
                     PP_InputEvent_Type type,
                     PP_TimeTicks time_stamp,
-                    Var text,
+                    const Var& text,
                     const std::vector<uint32_t>& segment_offsets,
                     int32_t target_segment,
                     const std::pair<uint32_t, uint32_t>& selection);
 
   /// Returns the composition text as a UTF-8 string for the given IME event.
   ///
   /// @return A string var representing the composition text. For non-IME
   /// input events the return value will be an undefined var.
   Var GetText() const;
 
@@ skipping 30 matching lines @@
 
   /// Returns the range selected by caret in the composition text.
   ///
   /// @return A pair of integers indicating the selection range.
   std::pair<uint32_t, uint32_t> GetSelection() const;
 };
 
 }  // namespace pp
 
 #endif  // PPAPI_CPP_DEV_IME_INPUT_EVENT_DEV_H_