Split out const/non-const variants of Resource::resourceRequest().

This patch follows the general convention of *::resourceRequest() and
*::mutableResourceRequest() from various other classes which use
ResourceRequest objects (FetchRequest, NavigationAction, etc).

As a drive-by, it also consts Resource::lastResourceRequest(), which was
already returning a const reference.

NOTRY=true

Review URL: https://codereview.chromium.org/424083002

git-svn-id: svn://svn.chromium.org/blink/trunk@179143 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/fetch/Resource.cpp

@@ -350,7 +350,7 @@ static bool canUseResponse(ResourceResponse& response, double responseTimestamp)
     return currentAge(response, responseTimestamp) <= freshnessLifetime(response, responseTimestamp);
 }
 
-const ResourceRequest& Resource::lastResourceRequest()
+const ResourceRequest& Resource::lastResourceRequest() const
 {
     if (!m_redirectChain.size())
         return m_resourceRequest;

third_party/WebKit/Source/core/fetch/Resource.h

@@ -111,8 +111,10 @@ public:
 
     virtual bool shouldIgnoreHTTPStatusCodeErrors() const { return false; }
 
-    ResourceRequest& resourceRequest() { return m_resourceRequest; }
-    const ResourceRequest& lastResourceRequest();
+    ResourceRequest& mutableResourceRequest() { return m_resourceRequest; }
+    const ResourceRequest& resourceRequest() const { return m_resourceRequest; }
+    const ResourceRequest& lastResourceRequest() const;
+
     const KURL& url() const { return m_resourceRequest.url();}
     Type type() const { return static_cast<Type>(m_type); }
     const ResourceLoaderOptions& options() const { return m_options; }

third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp

@@ -751,7 +751,7 @@ ResourcePtr<Resource> ResourceFetcher::requestResource(Resource::Type type, Fetc
     if (!request.forPreload() || policy != Use) {
         ResourceLoadPriority priority = loadPriority(type, request);
         if (priority != resource->resourceRequest().priority()) {
-            resource->resourceRequest().setPriority(priority);
+            resource->mutableResourceRequest().setPriority(priority);
             resource->didChangePriority(priority, 0);
         }
     }

third_party/WebKit/Source/core/fetch/ResourceLoadPriorityOptimizer.cpp

@@ -101,7 +101,7 @@ void ResourceLoadPriorityOptimizer::updateImageResourcesWithLoadPriority()
             ResourceLoadPriorityLow : ResourceLoadPriorityVeryLow;
 
         if (priority != it->value->imageResource->resourceRequest().priority()) {
-            it->value->imageResource->resourceRequest().setPriority(priority, it->value->screenArea);
+            it->value->imageResource->mutableResourceRequest().setPriority(priority, it->value->screenArea);
             it->value->imageResource->didChangePriority(priority, it->value->screenArea);
         }
     }