UserGestureIndicator: remove many unnecessary calls to isMainThread

third_party/WebKit/Source/platform/UserGestureIndicator.h

Index: third_party/WebKit/Source/platform/UserGestureIndicator.h
diff --git a/third_party/WebKit/Source/platform/UserGestureIndicator.h b/third_party/WebKit/Source/platform/UserGestureIndicator.h
index 5cab2e0c690d05884219ad11a0204570c1b19ab7..ddd2efa25fe6741a2b86f4c4d24b29ed3ba386fd 100644
--- a/third_party/WebKit/Source/platform/UserGestureIndicator.h
+++ b/third_party/WebKit/Source/platform/UserGestureIndicator.h
@@ -94,11 +94,15 @@ class PLATFORM_EXPORT UserGestureIndicator final {
   WTF_MAKE_NONCOPYABLE(UserGestureIndicator);
 
  public:
+  // Note: All *ThreadSafe methods are safe to call from any thread. Their
+  // non-suffixed counterparts *must* be called on the main thread.

[kinuko, 2016/12/12 14:51:26]

Let's add: "Consider always using the non-suffixed one unless the code really
needs to be thread-safe" or something like that

[Charlie Harrison, 2016/12/12 15:20:47]

Done.

+
   // Returns whether a user gesture is currently in progress.
   // Does not invoke the UserGestureUtilizedCallback.  Consider calling
   // utilizeUserGesture instead if you know for sure that the return value
   // will have an effect.
   static bool processingUserGesture();
+  static bool processingUserGestureThreadSafe();
 
   // Indicates that a user gesture (if any) is being used, without preventing it
   // from being used again.  Returns whether a user gesture is currently in
@@ -111,8 +115,10 @@ class PLATFORM_EXPORT UserGestureIndicator final {
   // operations like creating a new process.
   // Like utilizeUserGesture, may invoke/clear any UserGestureUtilizedCallback.
   static bool consumeUserGesture();
+  static bool consumeUserGestureThreadSafe();

[kinuko, 2016/12/12 04:45:12]

We don't need this and currentTokenThreadSafe other than in
processingUserGestureThreadSafe?

If so I started to think we should probably just keep the non-thread-safe
versions but add a thread-safety check at the callsites for these two.  (Sorry
for saying opposite to my previous comments)

[Charlie Harrison, 2016/12/12 13:10:09]

We use currentTokenThreadSafe in DOMTimer, and we use this and
currentTokenThreadSafe in the WebUserGestureIndicator. These are few enough
locations that we can make the isMainThread() call at the callsites if you
prefer though.

[Charlie Harrison, 2016/12/12 15:20:47]

I don't think this comment was properly resolved. Is your L-G contingent on
removing these ThreadSafes and moving the isMainThread() check to callsites, or
are these enough places where having the ThreadSafe API makes sense?

[kinuko, 2016/12/12 15:37:49]

Sorry I hadn't explicitly responded to this one. I had forgotten the use case in
DOMTimer so I thought it probably gives a reason to have the thread-safe version
for this one-- but then I looked the code site again and now I have another
comment :)

 
   static UserGestureToken* currentToken();
+  static UserGestureToken* currentTokenThreadSafe();
 
   explicit UserGestureIndicator(PassRefPtr<UserGestureToken>);
   ~UserGestureIndicator();