Fuchsia: Prepare for OS_POSIX removal in Blink.

This cleans up multi-platform code paths selection and prepares for
the removal of OS_POSIX for the Fuchsia build.

Bug: 836416
Change-Id: Ia326c5b5f0f05d347ee52abc89ad69386761792f
Reviewed-on: https://chromium-review.googlesource.com/1033994
Commit-Queue: Fabrice de Gans-Riberi <fdegans@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556918}

third_party/blink/renderer/platform/heap/heap_page.h

@@ -954,11 +954,9 @@ inline uint32_t GetRandomMagic() {
 #if defined(OS_WIN)
   static const uintptr_t random2 =
       ~(RotateLeft16(reinterpret_cast<uintptr_t>(::ReadFile)));
-#elif defined(OS_POSIX)
+#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
   static const uintptr_t random2 =
       ~(RotateLeft16(reinterpret_cast<uintptr_t>(::read)));
-#else
-#error OS not supported
 #endif
 
 #if defined(ARCH_CPU_64_BITS)

third_party/blink/renderer/platform/web_thread.cc

@@ -10,7 +10,7 @@
 
 #if defined(OS_WIN)
 #include <windows.h>
-#elif defined(OS_POSIX)
+#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
 #include <unistd.h>
 #endif
 
@@ -36,7 +36,7 @@ WebThreadCreationParams& WebThreadCreationParams::SetFrameScheduler(
 #if defined(OS_WIN)
 static_assert(sizeof(blink::PlatformThreadId) >= sizeof(DWORD),
               "size of platform thread id is too small");
-#elif defined(OS_POSIX)
+#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
 static_assert(sizeof(blink::PlatformThreadId) >= sizeof(pid_t),
               "size of platform thread id is too small");
 #else

third_party/blink/renderer/platform/wtf/byte_order.h

@@ -33,7 +33,7 @@
 
 #include "build/build_config.h"
 
-#if defined(OS_POSIX)
+#if defined(OS_POSIX) || defined(OS_FUCHSIA)
 #include <arpa/inet.h>
 #endif
 

third_party/blink/renderer/platform/wtf/threading_primitives.h

@@ -41,15 +41,19 @@
 
 #if defined(OS_WIN)
 #include <windows.h>
-#endif
-
-#if defined(OS_POSIX)
+#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
 #include <pthread.h>
 #endif
 
 namespace WTF {
 
-#if defined(OS_POSIX)
+#if defined(OS_WIN)
+struct PlatformMutex {
+  CRITICAL_SECTION internal_mutex_;
+  size_t recursion_count_;
+};
+typedef CONDITION_VARIABLE PlatformCondition;
+#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
 struct PlatformMutex {
   pthread_mutex_t internal_mutex_;
 #if DCHECK_IS_ON()
@@ -57,15 +61,6 @@ struct PlatformMutex {
 #endif
 };
 typedef pthread_cond_t PlatformCondition;
-#elif defined(OS_WIN)
-struct PlatformMutex {
-  CRITICAL_SECTION internal_mutex_;
-  size_t recursion_count_;
-};
-typedef CONDITION_VARIABLE PlatformCondition;
-#else
-typedef void* PlatformMutex;
-typedef void* PlatformCondition;
 #endif
 
 class WTF_EXPORT MutexBase {

third_party/blink/renderer/platform/wtf/threading_pthreads.cc

@@ -32,7 +32,7 @@
 
 #include "build/build_config.h"
 
-#if defined(OS_POSIX)
+#if defined(OS_POSIX) || defined(OS_FUCHSIA)
 
 #include <errno.h>
 #include <limits.h>
@@ -270,4 +270,4 @@ void WillCreateThread() {
 
 }  // namespace WTF
 
-#endif  // defined(OS_POSIX)
+#endif  // defined(OS_POSIX) || defined(OS_FUCHSIA)