Use sequence numbers to synchronize enabling Pointer Capture (1/2)

InputReader only processes configuration change from its main thread.
This means that if there is more than one Pointer Capture change
request when the thread is busy or sleeping, it will only process the
latest one. To ensure requests to enable Pointer Capture are synchronized
with Dispatcher, we must use sequence numbers.

Requests to enable Pointer Capture have a sequence number. Requests to
disable Pointer Capture do not have a value.

Bug: 195312888
Test: atest inputflinger_tests
Test: manual with GeforceNow app, see bug.
Merged-In: I6ae9c5498dc2f783b4c7211fa3665d42e29d2919
Change-Id: I6ae9c5498dc2f783b4c7211fa3665d42e29d2919
diff --git a/services/inputflinger/dispatcher/InputDispatcher.h b/services/inputflinger/dispatcher/InputDispatcher.h
index 2436e73..b92b8ea 100644
--- a/services/inputflinger/dispatcher/InputDispatcher.h
+++ b/services/inputflinger/dispatcher/InputDispatcher.h
@@ -365,10 +365,12 @@
 
     // Keeps track of the focused window per display and determines focus changes.
     FocusResolver mFocusResolver GUARDED_BY(mLock);
-    // Whether the focused window on the focused display has requested Pointer Capture.
-    // The state of this variable should always be in sync with the state of Pointer Capture in the
-    // policy, which is updated through setPointerCaptureLocked(enabled).
-    bool mFocusedWindowRequestedPointerCapture GUARDED_BY(mLock);
+
+    // The enabled state of this request is true iff the focused window on the focused display has
+    // requested Pointer Capture. This request also contains the sequence number associated with the
+    // current request. The state of this variable should always be in sync with the state of
+    // Pointer Capture in the policy, and is only updated through setPointerCaptureLocked(request).
+    PointerCaptureRequest mCurrentPointerCaptureRequest GUARDED_BY(mLock);
 
     // The window token that has Pointer Capture.
     // This should be in sync with PointerCaptureChangedEvents dispatched to the input channel.
@@ -378,7 +380,7 @@
     void disablePointerCaptureForcedLocked() REQUIRES(mLock);
 
     // Set the Pointer Capture state in the Policy.
-    void setPointerCaptureLocked(bool enabled) REQUIRES(mLock);
+    void setPointerCaptureLocked(bool enable) REQUIRES(mLock);
 
     // Dispatcher state at time of last ANR.
     std::string mLastAnrState GUARDED_BY(mLock);