FontResource: use DCHECKs for confirmed CHECKs

We used CHECKs to confirm if these checks are valid and can survive
on Canary. Now that we know these are correct, let's make it back
to DCHECKs.

BUG=670638

Review-Url: https://codereview.chromium.org/2558433002
Cr-Commit-Position: refs/heads/master@{#437510}

third_party/WebKit/Source/core/loader/resource/FontResource.cpp

@@ -105,19 +105,15 @@ void FontResource::didAddClient(ResourceClient* c) {
 void FontResource::setRevalidatingRequest(const ResourceRequest& request) {
   // Reload will use the same object, and needs to reset |m_loadLimitState|
   // before any didAddClient() is called again.
-  // TODO(toyoshim): Change following CHECKs to DCHECKs once we confirm these do
-  // not fire.
-  CHECK(isLoaded());
-  CHECK(!m_fontLoadShortLimitTimer.isActive());
-  CHECK(!m_fontLoadLongLimitTimer.isActive());
+  DCHECK(isLoaded());
+  DCHECK(!m_fontLoadShortLimitTimer.isActive());
+  DCHECK(!m_fontLoadLongLimitTimer.isActive());
   m_loadLimitState = LoadNotStarted;
   Resource::setRevalidatingRequest(request);
 }
 
 void FontResource::startLoadLimitTimers() {
-  // TODO(toyoshim): Change CHECK() to DCHECK() if this can survive on Canary
-  // for some days. http://crbug.com/670638
-  CHECK(isLoading());
+  DCHECK(isLoading());
   DCHECK_EQ(m_loadLimitState, LoadNotStarted);
   m_loadLimitState = UnderLimit;
   m_fontLoadShortLimitTimer.startOneShot(fontLoadWaitShortLimitSec,
@@ -151,11 +147,7 @@ FontPlatformData FontResource::platformDataFromCustomData(
 }
 
 void FontResource::fontLoadShortLimitCallback(TimerBase*) {
-  // TODO(toyoshim): Change CHECK() to DCHECK() and remove if(!isLoading()) if
-  // this can survive on Canary for some days. http://crbug.com/670638
-  CHECK(isLoading());
-  if (!isLoading())
-    return;
+  DCHECK(isLoading());
   DCHECK_EQ(m_loadLimitState, UnderLimit);
   m_loadLimitState = ShortLimitExceeded;
   ResourceClientWalker<FontResourceClient> walker(clients());
@@ -164,11 +156,7 @@ void FontResource::fontLoadShortLimitCallback(TimerBase*) {
 }
 
 void FontResource::fontLoadLongLimitCallback(TimerBase*) {
-  // TODO(toyoshim): Change CHECK() to DCHECK() and remove if(!isLoading()) if
-  // this can survive on Canary for some days. http://crbug.com/670638
-  CHECK(isLoading());
-  if (!isLoading())
-    return;
+  DCHECK(isLoading());
   DCHECK_EQ(m_loadLimitState, ShortLimitExceeded);
   m_loadLimitState = LongLimitExceeded;
   ResourceClientWalker<FontResourceClient> walker(clients());