align WebMemoryPressureLevel with MemoryPressureListener::MemoryPressureLevel

MemoryPressureListener::MemoryPressureLevel enum has changed to 0, 1, 2.
Let's align WebMemoryPressureLevel with it

BUG=

Review-Url: https://codereview.chromium.org/2086833005
Cr-Commit-Position: refs/heads/master@{#402691}

content/renderer/render_thread_impl.cc

@@ -262,6 +262,20 @@ static_assert(static_cast<v8::MemoryPressureLevel>(
     base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL) ==
         v8::MemoryPressureLevel::kCritical, "critical level not align");
 
+// WebMemoryPressureLevel should correspond to base::MemoryPressureListener.
+static_assert(static_cast<blink::WebMemoryPressureLevel>(
+    base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE) ==
+        blink::WebMemoryPressureLevelNone,
+            "blink::WebMemoryPressureLevelNone not align");
+static_assert(static_cast<blink::WebMemoryPressureLevel>(
+    base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE) ==
+        blink::WebMemoryPressureLevelModerate,
+            "blink::WebMemoryPressureLevelModerate not align");
+static_assert(static_cast<blink::WebMemoryPressureLevel>(
+    base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL) ==
+        blink::WebMemoryPressureLevelCritical,
+            "blink::WebMemoryPressureLevelCritical not align");
+
 class WebThreadForCompositor : public WebThreadImplForWorkerScheduler {
  public:
   explicit WebThreadForCompositor(base::Thread::Options options)

third_party/WebKit/public/platform/WebMemoryPressureLevel.h

@@ -10,9 +10,9 @@ namespace blink {
 // These number must correspond to
 // base::MemoryPressureListener::MemoryPressureLevel.
 enum WebMemoryPressureLevel {
-    WebMemoryPressureLevelNone = -1,
-    WebMemoryPressureLevelModerate = 0,
-    WebMemoryPressureLevelCritical = 2,
+    WebMemoryPressureLevelNone,
+    WebMemoryPressureLevelModerate,
+    WebMemoryPressureLevelCritical,
 };
 
 } // namespace blink