[sensors]: Introduce the Generic Sensor API.

third_party/WebKit/Source/core/frame/UseCounter.h

Index: third_party/WebKit/Source/core/frame/UseCounter.h
diff --git a/third_party/WebKit/Source/core/frame/UseCounter.h b/third_party/WebKit/Source/core/frame/UseCounter.h
index 041542f3c63f9b33dda4a28700b1f2ea83d86990..495279c6b00588472fe10b2267f073b92ad1ece7 100644
--- a/third_party/WebKit/Source/core/frame/UseCounter.h
+++ b/third_party/WebKit/Source/core/frame/UseCounter.h
@@ -1149,6 +1149,8 @@ public:
         Entry_Remove_Method_IsolatedFileSystem = 1331,
         Entry_GetParent_Method_IsolatedFileSystem = 1332,
         Entry_ToURL_Method_IsolatedFileSystem = 1333,
+        DocumentCreateEventSensorErrorEvent = 1334,

[timvolodine, 2016/05/06 17:04:29]

doesn't seem to be used anywhere in this patch unless I am missing something?

[riju_, 2016/05/12 14:12:45]

Acknowledged. But I am creating a SensorErrorEvent idl, and the generated files
tell me UseCounter is needed. I guess we need to use this in a subsequent CL
when we construct a ALS sensor and then find out that there is no hardware. So
yes, its not used in this CL, but its part of general Sensor infrastructure,
hence i am keeping this in this CL.

[timvolodine, 2016/05/17 17:44:39]

hmm weird, do you mean the compiler complains about usecounter. Do we now need a
constant for every idl we make? seems unnecessary to measure this since the
sensor classes are meant to be subclassed aren't they?

[riju_, 2016/05/20 11:20:11]

SensorErrorEvent and SensorReadEvent are not subclassed.

Could be wrong, but, maybe things changed after
https://codereview.chromium.org/1673243002 ?

[timvolodine, 2016/05/24 15:30:35]

yeah the patch you are refereing to makes sense.. don't see histograms.xml there
though, not sure if it's needed in this patch (?) but it's fine with me

[riju_, 2016/05/25 15:07:17]

After this CL, https://codereview.chromium.org/1745913002/
if there is a change in Feature enum, we need to update histogram, else clang
format complains.

+        DocumentCreateEventSensorReadingEvent = 1335,
 
         // Add new features immediately above this line. Don't change assigned
         // numbers of any item, and don't reuse removed slots.