don't allow screenshots without the READ_FRAMEBUFFER permission

the recent screenshot rework allowed the older screenshot
interface to work without that permission

Change-Id: I6c4743f4591c81106e3b823d55a055f7b4907de1

include/gui/ISurfaceComposer.h

@@ -103,16 +103,23 @@ public:
             uint32_t reqWidth, uint32_t reqHeight,
             uint32_t minLayerZ, uint32_t maxLayerZ) = 0;
 
-    /* triggers screen off and waits for it to complete */
+    /* triggers screen off and waits for it to complete
+     * requires ACCESS_SURFACE_FLINGER permission.
+     */
     virtual void blank(const sp<IBinder>& display) = 0;
 
-    /* triggers screen on and waits for it to complete */
+    /* triggers screen on and waits for it to complete
+     * requires ACCESS_SURFACE_FLINGER permission.
+     */
     virtual void unblank(const sp<IBinder>& display) = 0;
 
     /* returns information about a display
      * intended to be used to get information about built-in displays */
     virtual status_t getDisplayInfo(const sp<IBinder>& display, DisplayInfo* info) = 0;
 
+    /* Capture the specified screen. requires READ_FRAME_BUFFER permission
+     * This function will fail if there is a secure window on screen.
+     */
     virtual status_t captureScreen(const sp<IBinder>& display,
             const sp<IGraphicBufferProducer>& producer,
             uint32_t reqWidth, uint32_t reqHeight,

services/surfaceflinger/SurfaceFlinger.cpp

@@ -2399,6 +2399,7 @@ status_t SurfaceFlinger::onTransact(
 {
     switch (code) {
         case CREATE_CONNECTION:
+        case CREATE_DISPLAY:
         case SET_TRANSACTION_STATE:
         case BOOT_FINISHED:
         case BLANK:
@@ -2417,6 +2418,7 @@ status_t SurfaceFlinger::onTransact(
             break;
         }
         case CAPTURE_SCREEN:
+        case CAPTURE_SCREEN_DEPRECATED:
         {
             // codes that require permission check
             IPCThreadState* ipc = IPCThreadState::self();