Remove unused features for in-process GL contexts.

android_webview/browser/aw_render_thread_context_provider.h

Index: android_webview/browser/aw_render_thread_context_provider.h
diff --git a/android_webview/browser/aw_render_thread_context_provider.h b/android_webview/browser/aw_render_thread_context_provider.h
index 839f1a9346d6c4ea4de0b5d8345d431c4e096450..0c4d0ba9f19eb70625fd20e06a57431ed85a78e2 100644
--- a/android_webview/browser/aw_render_thread_context_provider.h
+++ b/android_webview/browser/aw_render_thread_context_provider.h
@@ -10,7 +10,6 @@
 #include <memory>
 
 #include "base/macros.h"
-#include "base/synchronization/lock.h"
 #include "base/threading/thread_checker.h"
 #include "cc/output/context_provider.h"
 #include "gpu/command_buffer/service/in_process_command_buffer.h"
@@ -62,8 +61,6 @@ class AwRenderThreadContextProvider : public cc::ContextProvider {
 
   LostContextCallback lost_context_callback_;
 
-  base::Lock context_lock_;
-
   DISALLOW_COPY_AND_ASSIGN(AwRenderThreadContextProvider);
 };