Decouple GamepadSharedMemory into Blink.

Decouple GamepadSharedMemory into Blink.

BUG = 612330

[ke.he, 2016-12-15 14:11:00]

ke.he@intel.com changed reviewers:
+ blundell@chromium.org

[ke.he, 2016-12-15 14:11:01]

Hi, Colin, This is only a draft patch.
In order to pass the presubmit, I made some temporary changes, please ignore
them.

I found I was blocked before starting the layout test part as described in
email.

Thanks!

https://codereview.chromium.org/2580693003/diff/1/third_party/WebKit/Source/m...
File third_party/WebKit/Source/modules/gamepad/GamepadDispatcher.cpp (right):

https://codereview.chromium.org/2580693003/diff/1/third_party/WebKit/Source/m...
third_party/WebKit/Source/modules/gamepad/GamepadDispatcher.cpp:7: #include
"modules/gamepad/GamepadSharedMemoryReader.h"
Actually the GamepadSharedMemory can be merged into GamepadDispatcher. I didn't
start that step though.

https://codereview.chromium.org/2580693003/diff/1/third_party/WebKit/Source/m...
File third_party/WebKit/Source/modules/gamepad/GamepadSharedMemoryReader.cpp
(right):

https://codereview.chromium.org/2580693003/diff/1/third_party/WebKit/Source/m...
third_party/WebKit/Source/modules/gamepad/GamepadSharedMemoryReader.cpp:103:
//base::subtle::Atomic32 version;  // heke: using base namespace here,???
messy here, just to pass the presubmit. but I do need to figure out how to using
the base::subtle::Atomic32 in blink.

[ke.he, 2016-12-15 14:14:43]

https://codereview.chromium.org/2580693003/diff/1/content/renderer/renderer_b...
File content/renderer/renderer_blink_platform_impl.cc (left):

https://codereview.chromium.org/2580693003/diff/1/content/renderer/renderer_b...
content/renderer/renderer_blink_platform_impl.cc:1197: void
RendererBlinkPlatformImpl::SetPlatformEventObserverForTesting(
called by
https://cs.chromium.org/chromium/src/content/test/layouttest_support.cc?rcl=1...
for layout test purpose.

[ke.he, 2016-12-15 14:35:56]

https://codereview.chromium.org/2580693003/diff/1/content/renderer/renderer_b...
File content/renderer/renderer_blink_platform_impl.cc (left):

https://codereview.chromium.org/2580693003/diff/1/content/renderer/renderer_b...
content/renderer/renderer_blink_platform_impl.cc:813: void
RendererBlinkPlatformImpl::sampleGamepads(WebGamepads& gamepads) {
Before decoupling, sampleGamepads() is defined in Platform.h and is implemented
here which belongs to content layer. It means "blink ask outside to implement
sampleGamepads()".

After decoupling, sampleGamepads() can be implemented totally inside blink. It
becomes into "blink expose a interface to outside." The interface exposing is
necessary because there are calls from pepper:
https://cs.chromium.org/chromium/src/content/renderer/pepper/pepper_plugin_in...

I heard the change of blink interface is quite serious, I'm not sure if the such
kind of changes is ok.

https://codereview.chromium.org/2580693003/diff/1/third_party/WebKit/Source/m...
File third_party/WebKit/Source/modules/gamepad/GamepadSharedMemoryReader.cpp
(right):

https://codereview.chromium.org/2580693003/diff/1/third_party/WebKit/Source/m...
third_party/WebKit/Source/modules/gamepad/GamepadSharedMemoryReader.cpp:90: //
TRACE_EVENT0("GAMEPAD", "SampleGamepads"); //heke: Webkit trace.
TODO(), does all the Content level trace need be translated into Webkit trace?
or just delete it?

[blundell, 2016-12-15 18:44:37]

Hi Ke He,

Apologies, I wasn't able to get to this today. I'll look at it tomorrow. You've
exposed a number of interesting challenges here :).

[ke.he, 2016-12-16 03:30:03]

ke.he@intel.com changed reviewers:
+ leon.han@intel.com

[ke.he, 2016-12-16 03:30:03]

Hi, Colin, Sorry it is a very draft submit that many things are in "TODO"
status. It is the Layout-test which really blocks me.

Thanks:)