Add an auto-exposure lock feature to the Camera API.

Adds a new camera parameter for locking auto-exposure to its current
value. Also adds a function for checking if auto-exposure lock is
supported by the current platform.

Hidden for now.

Change-Id: Id452371191ab220318ce2cb98b8ee91bdde9aab6
diff --git a/camera/CameraParameters.cpp b/camera/CameraParameters.cpp
index 214cd4d..4f3da40 100644
--- a/camera/CameraParameters.cpp
+++ b/camera/CameraParameters.cpp
@@ -68,6 +68,8 @@
 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";
+const char CameraParameters::KEY_AUTO_EXPOSURE_LOCK[] = "auto-exposure-lock";
+const char CameraParameters::KEY_AUTO_EXPOSURE_LOCK_SUPPORTED[] = "auto-exposure-lock-supported";
 const char CameraParameters::KEY_MAX_NUM_METERING_AREAS[] = "max-num-metering-areas";
 const char CameraParameters::KEY_METERING_AREAS[] = "metering-areas";
 const char CameraParameters::KEY_ZOOM[] = "zoom";
@@ -82,6 +84,7 @@
 const char CameraParameters::KEY_PREFERRED_PREVIEW_SIZE_FOR_VIDEO[] = "preferred-preview-size-for-video";
 
 const char CameraParameters::TRUE[] = "true";
+const char CameraParameters::FALSE[] = "false";
 const char CameraParameters::FOCUS_DISTANCE_INFINITY[] = "Infinity";
 
 // Values for white balance settings.