Limit the number of printed entries in a queue

When debugging some input bugs, it takes a while to scroll through all
of the entries in waitQueues and outboundQueues.
For example, the count can be > 100 for some ANR scenarios.

Limit the number to 50 total entries printed: 25 oldest and 25 newest.
This quantity should be sufficient to figure out what's going on with
the queues.

Note: I could not reproduce the ANR anymore, so the latest patchset was
not tested using the first test procedure.

Bug: 160561987
Test: reproduce an ANR using monkey, then look at dumpsys input
adb shell monkey 10000
adb shell dumpsys input
Test: the above procedure, but without 'reproduce ANR'

Change-Id: I01d661e0a85cc5bfbf61fa4b23689e8b27daa84b
diff --git a/services/inputflinger/dispatcher/Entry.cpp b/services/inputflinger/dispatcher/Entry.cpp
index 4328e03..34fa239 100644
--- a/services/inputflinger/dispatcher/Entry.cpp
+++ b/services/inputflinger/dispatcher/Entry.cpp
@@ -70,12 +70,6 @@
     releaseInjectionState();
 }
 
-std::string EventEntry::getDescription() const {
-    std::string result;
-    appendDescription(result);
-    return result;
-}
-
 void EventEntry::release() {
     refCount -= 1;
     if (refCount == 0) {
@@ -99,8 +93,8 @@
 
 ConfigurationChangedEntry::~ConfigurationChangedEntry() {}
 
-void ConfigurationChangedEntry::appendDescription(std::string& msg) const {
-    msg += StringPrintf("ConfigurationChangedEvent(), policyFlags=0x%08x", policyFlags);
+std::string ConfigurationChangedEntry::getDescription() const {
+    return StringPrintf("ConfigurationChangedEvent(), policyFlags=0x%08x", policyFlags);
 }
 
 // --- DeviceResetEntry ---
@@ -110,8 +104,8 @@
 
 DeviceResetEntry::~DeviceResetEntry() {}
 
-void DeviceResetEntry::appendDescription(std::string& msg) const {
-    msg += StringPrintf("DeviceResetEvent(deviceId=%d), policyFlags=0x%08x", deviceId, policyFlags);
+std::string DeviceResetEntry::getDescription() const {
+    return StringPrintf("DeviceResetEvent(deviceId=%d), policyFlags=0x%08x", deviceId, policyFlags);
 }
 
 // --- FocusEntry ---
@@ -126,8 +120,8 @@
 
 FocusEntry::~FocusEntry() {}
 
-void FocusEntry::appendDescription(std::string& msg) const {
-    msg += StringPrintf("FocusEvent(hasFocus=%s)", hasFocus ? "true" : "false");
+std::string FocusEntry::getDescription() const {
+    return StringPrintf("FocusEvent(hasFocus=%s)", hasFocus ? "true" : "false");
 }
 
 // --- KeyEntry ---
@@ -153,12 +147,11 @@
 
 KeyEntry::~KeyEntry() {}
 
-void KeyEntry::appendDescription(std::string& msg) const {
-    msg += StringPrintf("KeyEvent");
+std::string KeyEntry::getDescription() const {
     if (!GetBoolProperty("ro.debuggable", false)) {
-        return;
+        return "KeyEvent";
     }
-    msg += StringPrintf("(deviceId=%d, source=0x%08x, displayId=%" PRId32 ", action=%s, "
+    return StringPrintf("KeyEvent(deviceId=%d, source=0x%08x, displayId=%" PRId32 ", action=%s, "
                         "flags=0x%08x, keyCode=%d, scanCode=%d, metaState=0x%08x, "
                         "repeatCount=%d), policyFlags=0x%08x",
                         deviceId, source, displayId, KeyEvent::actionToString(action), flags,
@@ -212,12 +205,12 @@
 
 MotionEntry::~MotionEntry() {}
 
-void MotionEntry::appendDescription(std::string& msg) const {
-    msg += StringPrintf("MotionEvent");
+std::string MotionEntry::getDescription() const {
     if (!GetBoolProperty("ro.debuggable", false)) {
-        return;
+        return "MotionEvent";
     }
-    msg += StringPrintf("(deviceId=%d, source=0x%08x, displayId=%" PRId32
+    std::string msg;
+    msg += StringPrintf("MotionEvent(deviceId=%d, source=0x%08x, displayId=%" PRId32
                         ", action=%s, actionButton=0x%08x, flags=0x%08x, metaState=0x%08x, "
                         "buttonState=0x%08x, "
                         "classification=%s, edgeFlags=0x%08x, xPrecision=%.1f, yPrecision=%.1f, "
@@ -235,6 +228,7 @@
                             pointerCoords[i].getY());
     }
     msg += StringPrintf("]), policyFlags=0x%08x", policyFlags);
+    return msg;
 }
 
 // --- DispatchEntry ---