Unhide exposure compensation API.

bug:2375993
diff --git a/camera/CameraParameters.cpp b/camera/CameraParameters.cpp
index 1bf1759..8439e2b 100644
--- a/camera/CameraParameters.cpp
+++ b/camera/CameraParameters.cpp
@@ -60,7 +60,9 @@
 const char CameraParameters::KEY_HORIZONTAL_VIEW_ANGLE[] = "horizontal-view-angle";
 const char CameraParameters::KEY_VERTICAL_VIEW_ANGLE[] = "vertical-view-angle";
 const char CameraParameters::KEY_EXPOSURE_COMPENSATION[] = "exposure-compensation";
-const char CameraParameters::KEY_SUPPORTED_EXPOSURE_COMPENSATION[] = "exposure-compensation-values";
+const char CameraParameters::KEY_MAX_EXPOSURE_COMPENSATION[] = "max-exposure-compensation";
+const char CameraParameters::KEY_MIN_EXPOSURE_COMPENSATION[] = "min-exposure-compensation";
+const char CameraParameters::KEY_EXPOSURE_COMPENSATION_STEP[] = "exposure-compensation-step";
 
 // Values for white balance settings.
 const char CameraParameters::WHITE_BALANCE_AUTO[] = "auto";
diff --git a/include/camera/CameraParameters.h b/include/camera/CameraParameters.h
index e328f33..9df2695 100644
--- a/include/camera/CameraParameters.h
+++ b/include/camera/CameraParameters.h
@@ -187,16 +187,23 @@
     // Vertical angle of view in degrees.
     // Example value: "42.5". Read only.
     static const char KEY_VERTICAL_VIEW_ANGLE[];
-    // Exposure compensation. The value is multiplied by 100. -100 means -1 EV.
-    // 130 means +1.3 EV.
-    // Example value: "0" or "133". Read/write.
+    // Exposure compensation index. 0 means exposure is not adjusted.
+    // Example value: "0" or "5". Read/write.
     static const char KEY_EXPOSURE_COMPENSATION[];
-    // Supported exposure compensation.
-    // Example value: "-100,-66,-33,0,33,66,100". Read only.
-    static const char KEY_SUPPORTED_EXPOSURE_COMPENSATION[];
+    // The maximum exposure compensation index (>=0).
+    // Example value: "6". Read only.
+    static const char KEY_MAX_EXPOSURE_COMPENSATION[];
+    // The minimum exposure compensation index (<=0).
+    // Example value: "-6". Read only.
+    static const char KEY_MIN_EXPOSURE_COMPENSATION[];
+    // The exposure compensation step. Exposure compensation index multiply by
+    // step eqals to EV. Ex: if exposure compensation index is 6 and step is
+    // 0.3333, EV is -2.
+    // Example value: "0.333333333" or "0.5". Read only.
+    static const char KEY_EXPOSURE_COMPENSATION_STEP[];
 
 
-        // Values for white balance settings.
+    // Values for white balance settings.
     static const char WHITE_BALANCE_AUTO[];
     static const char WHITE_BALANCE_INCANDESCENT[];
     static const char WHITE_BALANCE_FLUORESCENT[];